In search of orthodontic materials

Orthodontics is a Greek word. Ortho means straight and dontics mean teeth. Orthodontics means straightening of crooked teeth. When the profile changes by changing the relations of the jaw bones i.e. maxilla and mandible, it is called dentofacial orthopedics. Banding, when it was first started in the early twentieth century, was done with gold and was prohibitively expensive even in the USA. With the advent of stainless steel, the cost of treatment came down but in India only the elite could afford it. Buonocore (1) introduced acid etching of the enamel with 37% orthophophoric acid gel, which made direct bonding possible. Bowen (2) resin was used for bonding of the brackets. This was more esthetic and less metallic, less painful and saved chair time. After bonding, wires were placed in the brackets, which delivered forces for the teeth to be moved. Now brackets are bonded directly on the teeth. These may be Edgewise or Begg or ceramic or self-ligating. More recent brackets are precoated adhesive brackets with moisture insensitive primer. Wire follows the brackets. The most popular wire is the A.J. Wilcock Australian, which comes in spools. It is bent by the orthodontist into the desired shaped to get the right forces. Ni Ti wire is preformed, cannot be bent and is expensive. This wire gives light continuous force. Rectangular wire is either of Truchrome or Elgiloy. It gives three-dimensional control of the teeth. It can be bent by the orthodontist. TMA wires are also gaining popularity as they can be bent and they give light continuous forces. α-Titanium wires are used for finishing a case. The wires are tied to the brackets with stainless steel ligatures, with Teflon coated ligatures or with modules. Extra oral headgears are used to control anchorage, distal drive the molars and to redirect growth in young patients. Elastics are worn and changed by the patient daily. They come in different sizes and colors. The force should be around 2-6 ounces and it can be measured with a Dontrix gauge. A positioner is made with Bioplast material using a Biostar machine. This is flexible and gives the final positioning of the teeth, reducing the fixed appliance treatment time by 6 months. A fixed light cure retainer prevents further relapse. Magnets are used to bring impacted teeth into occlusion and reinforce the forces of many removable appliances. From the IIT Madras days, till now we have developed and evaluated some materials in India. Standard band material consists of 304 L St. Steel. Chitra band material 3-8 was made with 316 L St. steel with the help of Mishra Dhatu Nigam, a govt. of India undertaking, with the financial support from ICMR. It contained Mo and Mn and had better adaptability and weld strength. Clinical trials done at CODS, Manipal showed it to be more effective than the rocky mountain band. The band is adapted with the use of the orthodontic pliers and a spot welder is used. It is then cemented on the tooth with Zn PO₄ cement (9). This was also developed at SCTMI and the paper published in 1991 in JPFA. Composites were used for bonding. We have developed four types of composites (10-16) with financial support from DST at SCTM in Trivandrum. These are chemical cure, light cure, radio opaque and polyurethane based composites. Clinical trials of these composites have been done in CODS Manipal and the materials found to be suitable for clinical use. In the last thirty years, a humble beginning was made in the field of orthodontic materials Stainless steel band material, Zn PO₄ cement and four types of composites have been developed and clinical trials conducted. However, the bottleneck is at the level of transfer of technology and commercial production. Once these materials are available in the market, the cost of orthodontic treatment will come down and it will become available to the common man in India. Further work needs to be done for the development of brackets and wires to make India self-sufficient.