4. DESCRIPTION
Field of the Invention
The present innovation relates to a novel method of training dental students to obtain accurate dental radiographs with the aid of LASER guided Aiming Device.
Background of the Invention
Effective radiation protection of patients depends on justification of the examination and optimization of the procedure (Annals of the International Commission on Radiological Protection. 21; 1991: 1-3). Minimization of errors is a decisive step in radiation protection. According to a study, three major radiographic errors occurring in dental radiography were incorrect film placement

(49.9 %), cone-cutting (20.8 %), and incorrect vertical angulation (12.5 %). (J.R. Patel Oral Surg. Oral Med. Oral Path. 48; 1979, 479-483). LASERs have been used in dental radiography for the purpose of patient positioning in panoramic imaging (Lambert PM, Gorman LM, Karimnamazi H, Kuthy RA, 1993, Implant Dent. 2 (4); 251-6). Two types of collimators have been used in dentistry namely rectangular and circular. A study reported that rectangular collimation techniques produced more errors than round collimation techniques (Parks ET Oral Surg. Oral Med. Oral Path. 71; 1991, 509-13). However, a rectangular collimator is more effective in reducing radiation dose because it produces an X-ray field similar to the size and shape of a size 2 dental film (Horton PS, Sippy FH, Nelson JF, Kohout FJ, Kienzle GC. J Dent Educ 1983; 47: 771-773). Rectangular collimators are not as widely used as circular in clinical practice because using rectangular cone generates more repeats due to conecut.13 - 15 Since the X-ray field is similar to the size and shape of a size 2 dental film, there is only a small margin for error in placing the cone (Van Straaten FJ, Van Aken J. Oral Surg Oral Med Oral Pathol 1982; 54: 347-359) (Kaugars GE, Broga DW, Collett WK. Oral Surg Oral Med Oral Pathol 1985; 60: 225-229.)
Earlier, a study to assess the effect of a laser guided collimator in intra-oral radiography training was conducted which employed the use of four red laser diodes on each corner of the rectangular collimator (ACM Chau, TKL Li and J Wong, Dento Maxillo Fac. Radiol., 2006). They observed that the laser-guided collimator device resulted in the reduction of the total number of repeats in a group of inexperienced students, especially in taking radiographs without an aiming device. Our innovation is aimed at improving the learning ability of an undergraduate student in aiming the circular position indicating device accurately on an extra oral landmark so as to reduce the occurrence of a cone-cut.

Summary of the Invention
LKAiD is made of a Polymethylmethacrylate ring and plate (PMMA) along with a laser situated in the centre of the ring with casings for the LR-44 AAA batteries by the periphery of the PMMA ring. Method of use is as follows:
1) Attach LKAiD to the circular position indicating device.(Figure 2A)
2) Position the circular position indicating device at the corresponding extra oral anatomical landmark (As per the Instruction Manual)
3) Press LASER switch on top of the LKAiD to confirm accuracy of targeting the Position Indicating device at the extra oral landmark.

4) Uncap LKAiD from the position indicating device
5) Proceed with routine radiographic procedure.
LKAiD is a simple invention that would assist dental students with no prior experience of making dental X-rays, in aiming the Circular Position Indicating Device at extra oral landmarks to obtain radiographs of specific teeth with greater accuracy.
Detailed description of the invention
A wax ring of 3.3 cms thickness and 7.5cms in diameter was prepared around a circular Position Indicating device. This circular wax ring was invested in a mould of dental stone and cured using Polymethylmethacrylate (PMMA). A wax plate of 7.5 cms diameter was also invested in dental stone and later cured using Polymethylmethacrylate. The surfaces of the ring and the plate were polished and assembled. A Class II ANSI Z136.1 LASER was fixed at the centre of the Polymethylmethacrylate plate. Three LR-44 AAA batteries were encased in a metal tubing located at the bottom of the Polymethylmethacrylate ring. A switch connecting the batteries and the LASER

Medicine And Radiology, A. B. Shetty Memorial Institute of Dental Sciences, NITTE University. The students were divided into two groups of twenty students each (Group A & Group B). Group A students were given a demonstration of the bisecting angle intra oral periapical radiographic technique with the LKAiD. Group B students were also given the same demonstration without the LKAiD. The students were made to perform radiographic procedure on the phantom heads. The radiographs blinded and evaluated by a staff not associated with the study from the Department of Oral Medicine and Radiology and were classified as Excellent, Acceptable and Repeat (According to criteria used by ACM Chau, TKL Li and J Wong, Dento Maxillo Fac. Radiol., 2006). When a statistical comparison was of the cone-cuts generated in 200 radiographs were assessed, it was found that Group A fared better than Group B.

5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -"I/We claim" on separate page)
"We claim that the use of (LKAiD) is a novel method for training of students in dental radiography. The device is more accurate than the conventional circular unaided position indicating device."