Mehta Sa, Gupta Ka, Valiathan Ab, Urala Ac, Thomas Bd, Bhat GSe
a – Postgraduate Student, Manipal College of Dental Sciences, Manipal, India.
b – Professor, Department of Orthodontics and Dentofacial Orthopedics, Manipal College of Dental Sciences, Manipal, India.
c – Reader, Department of Orthodontics and Dentofacial Orthopedics, Manipal College of Dental Sciences, Manipal, India.
d – Professor, Department of Periodontics, Manipal College of Dental Sciences, Manipal, India.
e – Professor, Department of Periodontics, Manipal College of Dental Sciences, Manipal, India.
Professor Ashima Valiathan
BDS (Pb), DDS, MS. (USA), FDSRCPS(Glasgow).
Department of Orthodontics and Dentofacial Orthopedics,
Manipal College of Dental Sciences,
Tel no: (0820)2922184, Mobile: 09886100125
Email id: email@example.com
After their introduction by Kanomi1 in 1997, microimplants have become a sensation enabling diverse clinical applications. Orthodontic miniscrews have been used to provide stable skeletal anchorage for both direct and indirect orthodontic traction. One of the challenges of microimplant placement is planning its correct positioning in the bone to achieve proper stability. The insertion technique should maximize the available bone volume while avoiding adjacent anatomical structures such as dental roots, nasomaxillary cavities, and neurovascular tissues.2
There is no doubt that the radiographic method is more reliable than clinical observation because it is unaffected by tooth movement, but its disadvantage is the difficulty of interpreting and applying the results in clinical practice.3 Three dimentional CT (computed tomography) scans provide detailed information on potential implant sites such as bone depth and density, but they are expensive and associated with radiation exposure. We just recommend a simple clinical maneuver – “Bone Sounding” to acquire an understanding of the bone level and thickness of the soft tissue overlying the bone.
In this technique a periodontal probe (or an endodontic spreader or file with a stopper) is used to measure the probing depth following local anesthesia administration (figure 1). Insertion into attached gingiva is preferable; therefore the probe or the spreader is used to punch the soft tissue in the desired safe area. The deepest point at which the probe meets strong resistance from contact to the bone is recorded as the bone probing depth. A microimplant is then placed in an area where bone probing depth is minimum and thus the soft tissue thickness least (figure 2). This can be especially useful when placing microimplants in the palatal region where greater variations of the soft-tissue thickness have been reported compared to the variations of the cortical bone thickness4.
The case below shows attempts to place a palatal microimplant (1.3 mm×9mm) in a patient with thick mucosa and high arched palate (figure 3). Since the mucosa was thick it provided an instant dip hence microimplant failed twice. Theoretically, a microimplant should be placed 4 to 8 mm from the gingival crestin the palatal tissuebetween first molar and second premolar5. Though placed in the same range, the implant failed. Clinically bone sounding was performed and the probe was moved in the adjacent area to determine the site with the least probing depth. The same miniscrew was then placed at that site which proved to be successful (figure 4). The bone probing depth at failure site was found to be around 5mm and the site of successful placement had probing depth of 3mm.
This knowledge allows the clinician to place a microimplant in sound bone and, therefore, increases the success rate.
- Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod 1997;31:763-67.
- Park HS, Jeong SH, Kwon OW. Factors affecting the clinical success of screw implants used as orthodontic anchorage. Am J Orthod Dentofacial Orthop 2006;130:18-25.
- Bjorn Ludwig, Bettina Glasl, S. Jay Bowman, Benedict Wilmes, Gero S.M. Kinzinger, Jorg A. Lisson. Anatomical Guidelines for Miniscrew Insertion: Palatal Sites. J Clin Orthod 2011;45:433-41.
- Kim HJ, Yun HS, Park HD, Kim DH, Park YC. Soft-tissue and cortical-bone thickness at orthodontic implant sites. Am J Orthod Dentofacial Orthop. 2006;130:177-82.
- Bong-Kuen Cha, Yeon-Hee Lee, Nam-Ki Lee, Dong-Soon Choi, Seung-Hak Baek. Soft Tissue Thickness for Placement of an Orthodontic Miniscrew Using an Ultrasonic Device. Angle Orthod 2008;78(3):403-8.