| Abstract|| |
Background: Right-left confusion in dental practice may lead to iatrogenic mishaps and thus can be of serious concern with respect to the patient care. Hence, the purpose of this study was to assess the right-left discrimination (RLD) ability among dental students. The study aims to determine the relation of various factors that can affect the students' discriminating ability.
Materials and Methods: All consented dental students from first year to fourth year were asked to mention their gender, course year, and handedness. They were also asked to record their perceived discriminatory ability on a five-point Likert scale and to mention the use of any method to aid in right-left discrimination. Modified Bergen test was used to determine the ability of the participants to differentiate right from left. The test had three subsections - all figures viewed from front, from back, and alternating views from back and front. The values obtained were statistically analysed.
Results: There was no significant difference in the RLD ability between males (43.25 ± 4.52) and females (42.12 ± 4.53). Even the discriminatory ability had no significant association with students' clinical exposure. Students who used learnt technique for differentiation had significantly lower scores (41.95 ± 4.58) than those without any technique (43.40 ± 4.30).
Conclusion: There was no significant association between gender and clinical exposure in the right-left discrimination ability among the dental students. Students who did not use any technique to aid them in differentiating right and left performed better than those who used some technique. Right-left confusion was more in situations where mental rotation was required.
Keywords: Clinical exposure, dental students, gender, mental rotation, right - left discrimination
|How to cite this article:|
Thomas MS, Kini S, Mala K. Factors affecting the right and left discrimination ability among dental students. J Educ Ethics Dent 2013;3:66-70
|How to cite this URL:|
Thomas MS, Kini S, Mala K. Factors affecting the right and left discrimination ability among dental students. J Educ Ethics Dent [serial online] 2013 [cited 2019 Dec 10];3:66-70. Available from: http://www.jeed.in/text.asp?2013/3/2/66/136047
| Introduction|| |
Discriminating left from right is a useful and sometimes crucial ability in everyday human life.  The ability to discriminate right from left requires several higher functions that include memory, visuospatial processing, language, integration of sensory information and mental rotation.  Scientific studies reported that healthy adults sometimes experience difficulty when telling left from right. These individuals have difficulty in either distinguishing right from left in them and/or in others. 
Dentists usually carry out the dental procedures either from the patient's front, patient's side or from the patient's back. Even the tooth nomenclature system commonly used; the Zygmondy-Palmer system is labeled in 'dentist's view', that is patient's right corresponds to the tooth chart's left side. Hence, the designations 'left' and 'right' in this nomenclature system corresponds to the patient's left and right, respectively. Therefore, the right and left discriminatory ability need to be sharper in a dentist as many a times the operations are associated with mental rotation.
Right and left confusion among dental clinicians can result in investigations and dental procedures being carried out on the wrong side/tooth (e.g. documenting the wrong tooth in the patient's file, taking a radiograph for a wrong quadrant, preparing cavity or initiating root canal treatment in a wrong tooth, or even extracting the wrong tooth etc.). This sort of errors can undermine the trust of the patient in the clinician and moreover can lead to medico-legal problems. Such mistakes may occur more frequently than what is reported, and prevention should start at the undergraduate level. Correctly discriminating right from left or vice versa is important in the practice of dentistry.
Measuring the discriminatory ability of students who report such problems may make them more vigilant and help them develop strategies to prevent errors in clinical practice.  Hardly any studies have been reported in the literature on the right-left discrimination (RLD) ability among dental students. Hence, the objective of this study was to identify the relationship between gender and clinical exposure on right-left confusion. The study also aims to evaluate the association between the techniques used to differentiate right from left and the actual RLD ability.
| Materials and Methods|| |
The research protocol was submitted to the Institutional Ethical Committee, and the approval was granted on January 7, 2013. All the consented undergraduate dental students from first to fourth year were given an anonymized questionnaire to ascertain the age, sex, and the class in which they are studying. The students were also asked to record their perceived discriminatory ability on a five-point Likert scale. A modified Oldfield handedness inventory (Revised Edinburgh Handedness Inventory) was used to determine their hand preference. The students were also requested to mention the use of any method to aid in right-left discrimination. Only students with right hand preference were included in the study to control the handedness.
Modified Bergen right-left discrimination test (paper and pen test using cartoon figures) was used to determine the ability of the participants to discriminate right from left. In this test, stick-man figures have a smiley when viewed from the front and a black head when viewed from the back [Figure 1]. Hands are circles at the end of the figures' arms. The test has three subsections - all figures viewed from the front, from the back, and alternating views from the back and front. For each subtest there were drawings of figures with no arm, one armor both the arms crossing the vertical axis [Figure 1].  Participants were shown two figures per slide with the help of power point projection. The subject's task was to mark whether the hand marked in red was either left (L) or right (R) adjacent to the number in the paper provided to them. Each slide was projected on the screen for 6 s. The images were projected in a randomized manner. In each subsection there were 16 figures. Therefore, the stimulus set consists of 48 line drawings. This gives a maximum potential score of 48 and a minimum score of 0.
The final data of the study results were compiled and the data were statistically analyzed using SPSS version 16.0 (SPSS Inc., Chicago IL). Statistical significance was checked for the discrimination ability among males and females, among students without and with clinical exposure and also among those who used learnt technique for differentiation and those who did not using student paired t-test. The correlation between the score and the orientation of figure (i.e. the results in each sub-section) were checked using Pearson correlation. The score and the students perceived discrimination ability were compared using ANOVA and posthoc test using Tukey HSD. Using this method, variables which showed P value <0.05 were considered statistically significant.
| Results|| |
A total of 332 students participated in the study. Out of which 22 students were excluded from the study (nine left-handed participants and 13 incomplete questionnaires). The descriptive statistics have been depicted in [Figure 2]. There was no significant difference in the RLD ability between males (43.25 ± 4.52) and females (42.12 ± 4.53) [Table 1]. Even the discriminatory ability had no significant association with students' clinical exposure. The details of the various methods used for RLD have been depicted in [Figure 3]. Students who used learnt technique for differentiation had significantly lower scores (41.95 ± 4.58) than those who used no technique (43.40 ± 4.30) [Table 1]. There was a significant correlation between the perceived ability and the test scores [Table 2]. The degree of difficulty in discrimination was mostly in the alternate view (13.14 ± 1.98) followed by the front view (14.57 ± 1.74) than the backward view (14.66 ± 1.86).
|Figure 3: Techniques used by participants to discriminate right and left|
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| Discussion|| |
Right and left differentiation (RLD) requires several cognitive abilities. The two vital steps in RLD is said to be the perceptual or spatial encoding process and the verbal coding process.  The first stage requiring spatial ability is thought to be lateralized to the right hemisphere of the brain. The second step which labels the side with the word right or left is supposed to be a left hemisphere task.  Various studies have employed different methods to determine the RLD ability. Some of these methods are egocentric,  that is, it is conducted from a participant's own viewpoint and therefore never involves mental rotation (e.g. Left-Right Commands Task by Hirnstein et al.  ). Mental rotation refers to the ability to rotate mental representations of two- and three-dimensional objects.  Other techniques employed are extra-egocentric right-left discrimination tasks, where right-left decisions regarding objects outside the own body have to be performed, which may be confounded by mental rotation (e.g. navigating through a three-dimensional virtual maze by Jordan et al.  ). Here, right-left errors can be the consequence of either a failure in egocentric right-left confusion or mental rotation.  The conflicting results among various studies can be explained by the RLD task employed. 
In this study, modified Bergen Right-Left discrimination test was selected to determine the RLD ability as it was easy to perform and since it correlates to an extent to the clinical scenario. In this study, the degree of difficulty in determining the right and left was maximum in the alternating view followed by the front view as compared to the backward view. Viewing the stickman figures from the back depends primarily on the ability to make right-left discriminations. While viewing the figures from the front means that an additional cognitive operation of 180° mental rotation needs to be performed. Viewing figures that alternate between back and front projections means that the subjects have to alternate between two different lateralized processing strategies: right-left discrimination and mental rotation processing strategies. 
In this study, even though the male students outperformed the female students in the RLD test, there was no statistical significance. This is in contrast to the results of several previous studies which showed that males performed significantly better than females in tasks requiring mental rotation due to superior right hemisphere visuo-spatial processing. ,, The reason for this could be because, the students, both males and females, who get selected for dental education have higher spatial abilities as compared to the general population.  Moreover, Jordan et al.  stated that simple RLD tasks did not reveal sex differences in right-left confusion, probably as a result of ceiling effect. Another reason for this ambiguous result could be because Bergan test do not always require mental rotation and that certain 'tactic knowledge' can be used for RLD. 
The ability to differentiate right from left needs to be sharper in dentists, as any lapse can lead to slipups. The position of the dentist with respect to the patient can keep varying during the procedure. The clinical procedures can be carried out by a right-handed operator either facing the patient (right front position), from the side of the patient (right position) or even from behind the patient (right rear/ direct rear position). For a left-handed operator, left is substituted for right.  Hence, right and left in a patient in relation to a dentist can keep changing depending on the dentists' chair position. Even the dental nomenclature used commonly used, the Zygmondy-Palmer system is one in which mental rotation is required. Hence, it was assumed that students with clinical experience would perform better than those with no clinical exposure because they would have developed some tactic in situations where mental rotation is required. Nevertheless the results from this study showed no statistical difference between the RLD ability among students with and without clinical exposure. This is in accordance with the study by Hegarty et al. which compared the performance of the second year and fourth year students on mental rotation, to show that education in dentistry does not improve one's ability to improve spatial ability more generally.
Majority of the students used some technique to aid them in differentiating right and left. These students scored significantly lower in the test when compared to that of those students who did not use any such discriminating technique. This is in accordance with the study by Gormely et al.  The reason for the better performance by participants who did not use any technique to aid in right-left discrimination can be because of a greater natural ability to discriminate than student who used a technique. The divergent strategies in various views would have led to a lower score in individuals using methods to differentiate right from left.
There was significant association with perceived discriminatory ability and test scores in the study. Hence, students who consider themselves to have poor discriminatory ability needs to be more cautious. Wrong sided dental events can have serious penalties. Hence, when learning relative anatomical directions such as mesial and distal, students should be told the importance of correctly differentiating right from left to ensure prevention of iatrogenic inadvertent dental mishaps, ensure patient safety and save dentists from medico-legal problems.  Dental educators need to emphasize the importance of differentiating right from left and it is also important for students to develop checks when making right-left decisions. Measuring the discriminatory ability of students who report such problems may help them develop strategies to prevent errors in clinical practice. Various strategies to prevent wrong sided events in dentistry are as follows: 
- Tooth numbering system used should be uniform. It is better to describe the tooth in long hand especially in cases of referral and in consent form.
- More informative referral slips with check boxes to reduce any ambiguity.
- Preoperative verification before any dental procedure.
- Marking the operation site or the radiograph.
- Ensure that radiographs are properly oriented and visually confirm that the correct teeth or tissues have been charted.
- Conduct a 'time out' to verify patient, tooth, and procedure with the assistant present at the time of dental procedure.
| Conclusion|| |
According to the results obtained from the study, there was no significant relationship between gender and clinical exposure among dental students in their ability to differentiate between right and left. On the contrary, students who did not use any learned technique for right-left discrimination performed significantly better when compared to those who used discriminating techniques. Moreover, right-left confusion was observed in situations where mental rotation was required. All students, especially those who consider themselves to have inferior discriminating ability need to be extra vigilant in the dental clinics to prevent wrong-sided dental mishaps. Further studies needs to be conducted to determine the effectiveness of the various strategies developed to prevent such occurrence related to right-left confusion.
| Acknowledgement|| |
We would like to thank Dr. Ramya Pai, Associate Professor, Department of Public Health Dentistry, Manipal College of Dental Sciences, Mangalore, Manipal University, for her assistance with the statistical analysis. We would also like to thank Mrs. Alka Anto for her help with the language check.
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Manuel Sebastian Thomas
Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Mangalore, Manipal University, Light House Hill Road, Mangalore - 575 001, Karnataka
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]