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| ORIGINAL ARTICLE |
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| Year : 2020 | Volume
: 8
| Issue : 4 | Page : 71-73 |
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Assessment of microsphere-controlled drug delivery for local control of tooth movement
Erukala Srikanth1, Eslavath Seena Naik1, Malledi Narasimha Lakshmi2, Devatha Ashok Babu3, Rahul Goud Padala4, Addu Aravind Kumar5
1 Department of Orthodontics and Dentifacial Orthopedics, Meghna Institute of Dental Sciences, Nizamabad, Telangana, India
2 Department of Orthodontics and Dentifacial Orthopedics, Govt. Dental College and Hospital, Hyderabad, Telangana, India
3 Department of Orthodontics and Dentifacial Orthopedics, GITAMS Dental College and Hospital, Visakhapatnam, Andhra Pradesh, India
4 Department of Orthodontics, Meghna Institute of Dental Sciences, Nizamabad, Telangana, India
5 Depatment of Periodontics, Meghna Institute of Dental Sciences, Nizamabad, Telangana, India
| Date of Submission | 04-Sep-2020 |
| Date of Acceptance | 03-Oct-2020 |
| Date of Web Publication | 27-Nov-2020 |
Correspondence Address:
Dr. Malledi Narasimha Lakshmi
Department of Orthodontics and Dentifacial Orthopedics, Govt. Dental College and Hospital, Afzalgunj Rd, near Police Station, Afzal Gunj, Hyderabad 500012, Telangana.
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/INJO.INJO_39_20
Background: Orthodontics is a special discipline dedicated to the investigation and practice of moving teeth through the bone. This study was conducted to assess new methods to locally enhance orthodontic anchorage. Materials and Methods: A single injection of 1 mg/kg nonencapsulated or microsphere encapsulated osteoprotegerin (OPG) was delivered into the palatal mucosa mesial to the first maxillary molar 1 day prior to tooth movement. A positive control group received injections of 5 mg/kg nonencapsulated OPG every 3 days during tooth movement. After 28 days of tooth movement, hemi-maxillae and femurs were dissected. Molar mesial and incisor distal tooth movement was measured using stone casts that were scanned and magnified. Results: Maximum movement was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG, 1 mg/kg encapsulated OPG, and 5 mg/kg nonencapsulated OPG. Maximum movement 2.6 mm was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG (2.4 mm), 1 mg/kg encapsulated OPG (2.5 mm), and 5 mg/kg nonencapsulated OPG (1.2 mm). A significant difference was found in bone mineral content, bone mineral density, tissue mineral content, and tissue mineral density with encapsulated and encapsulated OPG and microspheres (P < 0.05). Conclusion: Authors found that microsphere encapsulation of OPG allows for controlled drug release and enhances site-specific orthodontic anchorage without systemic side effects. Keywords: Microsphere encapsulation, orthodontic anchorage, rat
How to cite this article:
Srikanth E, Seena Naik E, Narasimha Lakshmi M, Ashok Babu D, Goud Padala R, Aravind Kumar A. Assessment of microsphere-controlled drug delivery for local control of tooth movement. Int J Oral Care Res 2020;8:71-3 |
How to cite this URL:
Srikanth E, Seena Naik E, Narasimha Lakshmi M, Ashok Babu D, Goud Padala R, Aravind Kumar A. Assessment of microsphere-controlled drug delivery for local control of tooth movement. Int J Oral Care Res [serial online] 2020 [cited 2021 Jan 24];8:71-3. Available from: https://www.ijocr.org/text.asp?2020/8/4/71/301702 |
| Introduction | |  |
Orthodontics is a special discipline dedicated to the investigation and practice of moving teeth through the bone. Moving teeth through the dentoalveolar complex is a synergistic sequence of physical phenomenon and biological tissue remodeling.[1] The tooth biological system reacts to variation in force magnitude, time of application, and directionality through receptor cells and signaling cascades that ultimately produce bone remodeling and orthodontic tooth movement (OTM).[2]
Osteoclasts are regulated via the nuclear factor kappa B ligand (RANKL)/nuclear factor kappa B (RANK)/osteoprotegerin (OPG) ligand-receptor system. In humans, injection with recombinant OPG or a monoclonal antibody to RANKL decreases serum markers of bone resorption, reduces fracture incidence, and increases bone mineral density.[3] Although systemic inhibition of osteoclast activity is beneficial for systemic disorders of bone, local inhibition of osteoclasts through controlled delivery of RANKL inhibitors would be useful for situations in which inhibition of bone resorption is desirable at specified locations, such as enhancement of orthodontic anchorage, or treatment of localized osteolytic disease.[4],[5] This study was conducted to assess new methods to locally enhance orthodontic anchorage.
| Materials and Methods | | |
In this study, a single injection of 1 mg/kg nonencapsulated or microsphere encapsulated OPG was delivered into the palatal mucosa mesial to the first maxillary molar 1 day prior to tooth movement. A positive control group received injections of 5 mg/kg nonencapsulated OPG every 3 days during tooth movement. After 28 days of tooth movement, hemi-maxillae and femurs were dissected. Molar mesial and incisor distal tooth movement was measured using stone casts that were scanned and magnified. Local alveolar, distant femur bone, and tooth root volumes were analyzed by microcomputed tomography. Serum OPG levels were measured by ELISA. Osteoclast numbers were quantified by histomorphometry. Results thus obtained were subjected to statistical analysis. A value of P < 0.05 was considered significant.
| Results | | |
Molar movement (mm) from microspheres
Results showed that maximum movement was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG, 1 mg/kg encapsulated OPG, and 5 mg/kg nonencapsulated OPG.
Incisor movement (mm) from microspheres
Results showed that maximum movement 2.6 mm was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG (2.4 mm), 1 mg/kg encapsulated OPG (2.5 mm), and 5 mg/kg nonencapsulated OPG (1.2 mm).
[Table 1] shows a significant difference in bone mineral content, bone mineral density, tissue mineral content, and tissue mineral density with encapsulated and encapsulated OPG and microspheres (P < 0.05). | Table 1: Maxillary molar furcation area bone density and mineral content
Click here to view |
| Discussion | | |
Orthodontic treatment involves the carefully controlled application of mechanical forces to teeth to obtain an optimal occlusal relationship. Because no fixed intraoral anatomical anchor exists, every applied orthodontic force will cause a counter-action of equal force, which is often accompanied by undesirable tooth movement. Orthodontic anchorage refers to methods for inhibiting these unwanted tooth movements.[6],[7] This study was conducted to assess new methods to locally enhance orthodontic anchorage.
We found that maximum movement was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG, 1 mg/kg encapsulated OPG, and 5 mg/kg nonencapsulated OPG.
The ability of teeth to move through the bone relies on the PDL, which attaches the tooth to the adjacent bone. The PDL is a dense fibrous connective tissue structure that consists of collagenous fiber bundles, cells, neural and vascular components, and tissue fluids. Its primary function is to support the teeth in their sockets while allowing teeth to withstand considerable chewing forces. On average, the PDL occupies a space about 0.2 mm wide. Depending on its location along the root, PDL width can range from 0.15 to0.38 mm, with its thinnest part located in the middle third of the root. PDL space also decreases progressively with age.[8]
Sydorak et al.[9] in their study found that the single injection of microsphere encapsulated OPG significantly enhanced orthodontic anchorage, whereas the single injection of nonencapsulated OPG did not. Injection of encapsulated OPG inhibited molar mesial movement but did not inhibit incisor tooth movement, and did not alter alveolar or femur bone volume fraction, density, or mineral content. Multiple injections of 5 mg/kg nonencapsulated OPG enhanced orthodontic anchorage but also inhibited incisor retraction and altered alveolar and femur bone quality parameters. Increased OPG levels were found only in animals receiving multiple injections of nonencapsulated 5 mg/kg OPG. Osteoclast numbers were higher upon tooth movement in animals that did not receive OPG.
We found that maximum movement 2.6 mm was obtained with an empty microsphere single injection as compared to 1 mg/kg nonencapsulated OPG (2.4 mm), 1 mg/kg encapsulated OPG (2.5 mm), and 5 mg/kg nonencapsulated OPG (1.2 mm). A significant difference was found in bone mineral content, bone mineral density, tissue mineral content, and tissue mineral density with encapsulated and encapsulated OPG and microspheres.
Poly(lactic-co-glycolic acid) (PLGA) microspheres are biocompatible and biodegradable. In this study, we found that a 50–50lactic-to-glycolic acid ratio resulted in faster drug release than a 75:25 ratio, which is consistent with previous studies. Notably, encapsulation of OPG using the 75–25 ratio significantly enhanced orthodontic anchorage without inhibiting overall tooth movement or entering the systemic circulation, but efficacy for inhibiting tooth movement was not to the same degree that could be achieved by injecting very high dose levels of nonencapsulated OPG.[10]
| Conclusion | | |
Authors found that microsphere encapsulation of OPG allows for controlled drug release and enhances site-specific orthodontic anchorage without systemic side effects.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Nanci A, Bosshardt DD Structure of periodontal tissues in health and disease. Periodontol 2000 2006;40:11-28.  |
| 2. | Schroeder HE The Periodontium. Berlin and Heidelberg: Springer; 1986. p. 152. |
| 3. | Ducy P, Schinke T, Karsenty G The osteoblast: A sophisticatedfibroblast under central surveillance. Science 2000;289:1501-4. |
| 4. | D’Ippolito G, Schiller PC, Ricordi C, Roos BA, Howard GA Agerelatedosteogenic potential of mesenchymal stromal stem cells from human vertebral bone marrow. J Bone Miner Res 1999;14:1115e22. |
| 5. | Boyle WJ, Simonet WS, Lacey DL Osteoclast differentiation and activation. Nature 2003;423:337-42. |
| 6. | Teitelbaum SL Bone resorption by osteoclasts. Science 2000;289:1504-8. |
| 7. | Wise GE, King GJ Mechanisms of tooth eruption and orthodontictooth movement. J Dent Res 2008;87:414-34. |
| 8. | Wise GE, King GJ Mechanisms of tooth eruption and orthodontictooth movement. J Dent Res 2008;87:414e34. |
| 9. | Sydorak I, Dang M, Baxter SJ, Halcomb M, Ma P, Kapila S, et al. Microsphere controlled drug delivery for local control of tooth movement. Eur J Orthod 2019;41:1-8. |
| 10. | Asiry MA Biological aspects of orthodontic tooth movement: A review of literature. Saudi J Biol Sci 2018;25: 1027-32. |
[Table 1]
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