Measuring tooth size discrepancies using Bolton analysis: a comparative cross-sectional study among major ethnicity in Malaysia.

BACKGROUND: The Bolton analysis is one of the commonly used tooth size analysis or diagnostic tools in deriving a treatment plan for orthodontic patients. Many studies have indicated and concluded that normal measurements for one group should not be considered normal for other ethnic groups. The aims and objectives of this study were to investigate the applicability of Bolton's ratios in the orthodontic population of Malaysian main ethnics, Malay, Chinese, and Indians. Comparisons were made in terms of size and distribution of tooth size discrepancy in the Malaysian orthodontic population and the findings were converted in terms of millimeters. METHODS: Hundred fifty pre-orthodontic study casts comprised of 52 Malay, 54 Chinese, and 44 Indian patients were selected. Digital calipers (Fowler Pro-Max) linked to Hamilton Tooth Arch Software were used to measure the tooth width and ratios. Statistical analysis was carried out to test for gender differences (independent t-test), to identify the effects of malocclusion and ethnic groups (Two-way ANOVA), and to compare the means of the current study with Bolton's standards (one sample t-test). RESULTS: This study showed that there was no significant difference between the genders of the sample of each ethnicity. There was no correlation found between ethnic groups and malocclusion classes. There was a significant difference when comparing Bolton values with the Malay sample for both ratios. It was found that more Malay subjects presented with maxillary excess contrary to Chinese and Indians who presented more maxillary deficiency for the anterior and overall ratio. CONCLUSION: There was a significant difference found between the TSD of the three major ethnicities in Malaysia. The Bolton standards can be applied to Malaysian Chinese and Indians but not to Malays orthodontic populations for both anterior and overall ratios. Subsequently, a specific standard should be used for the Malays orthodontic population. It was found that more Malay subjects presented with maxillary excess contrary to Chinese and Indians who presented more maxillary deficiency for the anterior and overall ratio.

Students' perception on flipped classroom with formative assessment: A focus group study.

OBJECTIVE: To explore students' perception on the implementation of flipped classroom (FC) combined with formative assessment during the undergraduate teaching of orthodontic wire-bending skills. METHODS: Third-year undergraduate dental students were taught wire-bending skills via FC teaching method using a series of pre-recorded online video demonstrations. As part of the formative assessment, the students were given the results and assessment rubrics of their prior wire-bending assessment before every subsequent session. Purposive sampling method for focus group discussion was used to recruit eight students comprising four high achievers and four low achievers. Strengths, weaknesses and suggestions for improvement of the FC with formative assessment were explored. Data were transcribed and thematically analysed. RESULTS: Students perceived that FC allowed for a more convenient and flexible learning experience with personalised learning and improved in-class teaching efficiency. The pre-recorded online videos were useful to aid in teaching wire-bending skills but lacked three-dimensional representation of the wire-bending process. Students suggested better standardisation of instructions and access to the marking rubric before and after assessment. CONCLUSIONS: FC teaching with continuous formative assessment and constructive feedback as a form of personalised learning was viewed favourably by students. The implementation of periodic individual feedback can further enhance their learning experience.

The effect of live demonstration and flipped classroom with continuous formative assessment on dental students' orthodontic wire-bending performance.

BACKGROUND: Wire-bending skills is commonly taught through live demonstrations (LD) though flipped classroom (FC) method has gained popularity. Continuous formative assessment promotes personalised learning via closely monitored progress, with the identification of students' strengths and weaknesses. This study aims to evaluate the effects of LD and FC teaching methods, supplemented with continuous formative assessment, on dental students' learning of wire-bending skills for six types of removable orthodontic appliance components. A deeper understanding of the relative effectiveness between LD and FC teaching methods can help identify the most appropriate method to achieve student learning objectives, which is especially important given the current Covid-19 pandemic. METHODS: Forty third-year undergraduate dental students were randomly assigned into FC (n = 20) or LD (n = 20) cohort. Each student attended six teaching sessions, each to teach students' competency in fabricating one type of wire component, for a total competency in fabricating six wire components over the course of six teaching sessions. Either LD or FC teaching methods were used. After each session, wire assignments had to be submitted. Wire assignments were then evaluated using a blinded wire-bending assessment protocol. As part of their formative assessment, the assessment results were distributed to students, lecturers, and technicians before the next session. After the first session (T0) and at the end of all six sessions (T1), students completed a self-reported questionnaire. RESULTS: The mean wire-bending scores for FC were significantly higher than LD for two of the six assignments, namely the Adams clasp (p < 0.01) and Z-spring (p = 0.03). Scores for both LD and FC increased significantly over time, which may be attributed to formative assessment. There was no statistically significant correlation between wire-bending scores and video usage. Students were satisfied with both teaching methods, according to T0 and T1 questionnaires. CONCLUSIONS: Both LD and FC are equally effective in transferring practical orthodontic wire-bending skills and well-received by students. Continuous formative assessment may have enhanced students' learning of orthodontic wire-bending skills. Further studies with control group are recommended to investigate the effect of formative assessment on teaching practical dental skills.

Oral health-related quality of life among 11-12 year old indigenous children in Malaysia.

BACKGROUND: Poor oral health among Malaysian indigenous Orang Asli (OA) children may impact on their daily performances. AIM: To assess the oral health status, related behaviours, and oral health-related quality of life (OHRQoL) among OA children in Cameron Highlands (CH), Malaysia, and to identify the predictor(s) for poor OHRQoL. DESIGN: This was a cross-sectional study involving 249, 11-12 year old OA children from 4 OA primary schools in CH. The children completed a self-administered questionnaire comprising information on socio-demographics, oral health-related behaviours, and the Malay Child Oral Impacts on Daily Performances (Malay Child-OIDP) index followed by an oral examination. Data were entered into the SPSS version 23.0 software. Non-parametric tests and multiple logistic regression were used for data analysis. RESULTS: The response rate was 91.2% (n = 227/249). The prevalence of caries was 61.6% (mean DMFT = 1.36, mean dft = 1.01) and for gingivitis was 96.0%. Despite the majority reported brushing their teeth ≥ 2x/day (83.7%) with fluoride toothpaste (80.2%), more than two-thirds chewed betel nut ≥ 1/day (67.4%). Majority of the children (97.8%) had a dental check-up once a year. Nearly three-fifths (58.6%) reported experiencing oral impacts on their daily performances in the past 3 months (mean score = 5.45, SD = 8.5). Most of the impacts were of "very little" to "moderate" levels of impact intensity with 90.2% had up to 4 daily performances affected. Most of the impacts were on eating (35.2%), cleaning teeth (22.0%) and relaxing activities (15.9%). Caries in primary teeth is associated with oral impacts among the OA children. CONCLUSIONS: The 11-12 year old OA children in Cameron Highland had high prevalence of caries and gingivitis with the majority chewed betel nut regularly. Caries in primary teeth is associated with poor OHRQoL. Future programmes should target younger age group children to promote positive oral hygiene practices, reduce caries, and improve quality of life.

Assessing agreement in measurements of orthodontic study models: Digital caliper on plaster models vs 3-dimensional software on models scanned by structured-light scanner.

INTRODUCTION: In this study we aimed to compare measurements on plaster models using a digital caliper, and on 3-dimensional (3D) digital models, produced using a structured-light scanner, using 3D software. METHODS: Fifty digital models were scanned from the same plaster models. Arch and tooth size measurements were made by 2 operators, twice. Calibration was done on 10 sets of models and checked using the Pearson correlation coefficient. Data were analyzed by error variances, repeatability coefficient, repeated-measures analysis of variance, and Bland-Altman plots. RESULTS: Error variances ranged between 0.001 and 0.044 mm for the digital caliper method, and between 0.002 and 0.054 mm for the 3D software method. Repeated-measures analysis of variance showed small but statistically significant differences (P <0.05) between the repeated measurements in the arch and buccolingual planes (0.011 and 0.008 mm, respectively). There were no statistically significant differences between methods and between operators. Bland-Altman plots showed that the mean biases were close to zero, and the 95% limits of agreement were within ±0.50 mm. Repeatability coefficients for all measurements were similar. CONCLUSIONS: Measurements made on models scanned by the 3D structured-light scanner were in good agreement with those made on conventional plaster models and were, therefore, clinically acceptable.

Reproducibility of facial soft tissue landmarks on facial images captured on a 3D camera.

OBJECTIVE: Fast and non-invasive systems of the three-dimensional (3D) technology are a recent trend in orthodontics. The reproducibility of facial landmarks is important so that 3D facial measurements are accurate and may-be applied clinically. The aim of this study is to evaluate the reproducibility of facial soft tissue landmarks using a non-invasive stereo-photogrammetry 3D camera. MATERIAL AND METHODS: Twenty-four soft tissue landmarks on 3D facial images captured using a VECTRA-3D dual module camera system for full face imaging (Canfield Scientific inc, Fairfield, NJ, USA) were viewed and analysed using Mirror software on 30 adult subjects (15 males and 15 females, in the age range of 20-25 years). The landmarks were identified, recorded and measured twice on each 3D facial image by one examiner after a 2-week interval. Intra-class correlations and paired t-test or Wilcoxon Rank test were performed for each landmark to assess intra-examiner reproducibility. RESULTS: Intra-class correlation coefficients for all 24 landmarks ranged from 0.68 to 0.97, indicating moderate to high reliability and reproducibility of all facial soft tissue landmarks. Paired t-tests and Wilcoxon Rank test also revealed that there were no significant differences in all 24 facial soft tissue landmarks measurements (p = 0. 17 - 0.99). CONCLUSION: The results indicated that the reproducibility of identification of landmarks by one operator on facial images captured using a VECTRA-3D camera was acceptable. This device may be useful in treatment planning and may provide accurate information in making clinical decisions. However, it is suggested that further studies on inter-examiner reproducibility should be undertaken.

Age and Gender Are Associated with the Component of Psychosocial Impact of Dental Aesthetics Questionnaire in Young People: A Cross-Sectional Study.

(1) The aim of the study was to investigate the association between age, gender, and the component of psychosocial impact of dental aesthetics (PIDAQ) in Malaysian young people. (2) Cross-sectional data on the PIDAQ (comprised of dental self-confidence, social impact, psychological impact, and aesthetic concern variables) of Malaysian youth (n = 1425) recruited through multi-stage sampling were analyzed for mediation and moderated mediation analyses using the PROCESS macro on SPSS software. (3) Participants (mean age 16.0 ± 2.8) represented 54.8% of girls and 45.2% of boys. In the mediation model, psychological impact and aesthetic concern completely mediated the effects of social impact on dental self-confidence. In the moderated mediation model, social impact directly influenced dental self-confidence amongst participants at one standard deviation below the sample mean age and among boys. However, psychological impact completely mediated the influence of social impact on dental self-confidence amongst participants at the sample mean age and at one standard deviation above the sample mean ages, and among girls. Neither age nor gender moderated the effect of aesthetic concern on dental self-confidence. (4) Age and gender moderated the influence of social impact and psychological impact on dental self-confidence.

Minimal Important Difference of the Psychosocial Impact of Dental Aesthetics Questionnaire Following Orthodontic Treatment: A Cohort Study.

(1) This study aimed to do a longitudinal validation of the psychosocial impact of dental aesthetics questionnaire (PIDAQ) and determine its minimal important difference (MID) following orthodontic treatment; (2) 42 adolescents (11 to 18 years old) were recruited for treatment with fixed appliances and the participants answered the Malaysian PIDAQ prior to treatment (T0), mid-treatment (T1), and post-treatment (T2), plus a global health transition scale at T1 and T2. Data analyses included repeated measures ANOVA and paired sample t-tests. Test-retest was administered 2 to 6 weeks from T0; (3) The final sample comprised 37 subjects (response rate = 88.1%). The 95% limits of agreement were -10.3 to 8.5 points. In the anchor-based approach, those who experienced the smallest changes by reporting their dental aesthetics as "a little improved" had an insignificant PIDAQ score change of -5.3 at T1. At T2, the PIDAQ scores of those in this category were reduced significantly (mean change = -26.2; effect size (ES) = 1.0; p = 0.34). In the distribution-based approach, standardized PIDAQ scores were significantly reduced, with medium (0.7) to large (1.5) ES at T1 and T2, respectively; (4) The PIDAQ can detect orthodontic-related changes in patients' psychosocial well-being. The post-treatment MID is 26 scale points with large ES.

Validation of the Simplified Malaysian Psychosocial Impact of Dental Aesthetics Questionnaire for the Sociodental Approach to Estimate the Orthodontic Treatment Need.

(1) This study aimed to generate a simplified form of the Malaysian psychosocial impact of dental aesthetics questionnaire (PIDAQ[M]) and validate its use in the sociodental approach for estimating orthodontic treatment need. (2) Two eight-item forms were derived: an impact simplified PIDAQ[M] (ISP8), comprising the most impactful items as rated by 35 participants, and a regression simplified PIDAQ[M] (RSP8), derived from regression analysis of 590 participants' data from the PIDAQ[M] validation study. Their psychometric performances were assessed for internal consistency, validity (criterion and construct), reproducibility (reliability and agreement), and responsiveness to change. The sociodental estimates were based on 204 orthodontic patients' data who were assessed for normative need, impact-related need, and propensity-related need. McNemar analysis compared the sociodental estimates when both simplified PIDAQ[M] forms and the original PIDAQ[M] were used to measure impact-related need. (3) Both simplified PIDAQ[M] forms were valid, reproducible, and responsive. The sociodental estimates when using the ISP8 (38.2%) were similar to when the PIDAQ[M] (35.8%) was used (p > 0.05) but overestimated by 3.4% (p < 0.05) when the RSP8 (39.2%) was used as the assessment tool. (4) The simplified PIDAQ[M] can replace the original PIDAQ[M] in the sociodental approach to estimate the orthodontic treatment needs of the Malaysian population.

Students' perception on flipped classroom in contrast to live demonstration for teaching orthodontic wire-bending skills: A focus group study.

OBJECTIVE: This study aimed to explore students' perceptions of flipped classroom (FC) compared to live demonstration (LD) in transferring skills of fabricating orthodontic wire components for orthodontic removable appliances. METHODS: Forty third-year undergraduate dental students were randomly assigned to two groups: FC (n = 20) and LD (n = 20). Students in group FC attended FC, while students in group LD attended LD. Both groups underwent a series of standardized teaching sessions to acquire skills in fabricating six types of orthodontic wire components. Eight students (four high achievers and four low achievers) from each group were randomly selected to attend separate focus group discussion (FGD) sessions. Students' perceptions on the strengths, weaknesses, and suggestions for improvement on each teaching method were explored. Audio and video recordings of FGD were transcribed and thematically analyzed using NVivo version 12 software. RESULTS: Promoting personalized learning, improvement in teaching efficacy, inaccuracy of three-dimensional demonstration from online video, and lack of standardization among instructors and video demonstration were among the themes identified. Similarly, lack of standardization among instructors was one of the themes identified for LD, in addition to other themes such as enabling immediate clarification and vantage point affected by seating arrangement and class size. CONCLUSIONS: In conclusion, FC outperformed LD in fostering personalized learning and improving the efficacy of physical class time. LD was more advantageous than FC in allowing immediate question and answer. However, seating arrangement and class size affected LD in contrast to FC.

Comparing flipped classroom and conventional live demonstration for teaching orthodontic wire-bending skill.

Flipped classroom may overcome weaknesses of live demonstration in teaching orthodontic wire-bending. This study aims to compare the effectiveness between flipped classroom and live demonstration in transferring skills for fabricating Adams clasp. Forty third-year undergraduate dental students were assigned to two groups. The students in group LD (n = 20) attended a live demonstration while students in group FC (n = 20) attended a flipped classroom. Both groups were taught on skills to fabricate Adams clasp in a standardised way. Each student from both groups were asked to submit an Adams clasp for a blinded quality assessment by two trained and calibrated assessors using a 18-item rubric, followed by validated students' satisfaction questionnaires to evaluate their perceived satisfaction on the teaching method received. A crossover study was then conducted three weeks later where LD attended a flipped classroom while FC attended a live demonstration. Students' satisfaction questionnaires were again collected from each student for blinded analysis. Mean scores for the quality of Adams clasp were 9.775 and 9.125 for LD and FC, respectively. No significant difference was detected between the two groups. Statistically significant association was found for one statement on the questionnaire, "I found the classroom arrangements conducive for the wire-bending activity" (p = 0.010). No significant differences were found between the two groups for other statements (p > 0.05). In conclusion, within the limitations of the study, flipped classroom is equally effective as conventional live demonstration in transferring orthodontic wire-bending skills for fabrication of Adams clasp. However, students perceived the classroom arrangements during the flipped classroom significantly more conducive for teaching orthodontic wire-bending.

Cephalometric analysis of Malay children with and without unilateral cleft lip and palate.

OBJECTIVE: To investigate the craniofacial morphology of Malay children with repaired UCLP and compare the data with non-cleft Malay children. METHODS: Twenty Malay children with repaired UCLP (12 boys, 8 girls; Mean age: 10.5 years) and 20 normal Malay children (8 boys, 12 girls; Mean age: 9.72 years) were recruited from the Combined Cleft Lip and Palate Clinic and the Department of Children's Dentistry and Orthodontics, Faculty of Dentistry, University of Malaya, Malaysia. Lateral cephalometric radiographs were taken with the head orientated parallel to the floor. Thirty-one linear and angular variables were measured on the lateral cephalometric radiographs with Dolphin Imaging Software Version 10.0 (Dolphin Imaging, Chatsworth, CA, USA). The data were analysed with the Mann-Whitney U test and the level of significance was set at p < 0.05. RESULTS: In the UCLP group, the girls had deeper overbites than the boys (p = 0.011), and in the Control group the girls had a significantly more acute cranial base angle (NSBa, p = 0.017) and a less protrusive lower lip (LL-E line, p = 0.21). The data for the boys and girls were combined. Subjects in the UCLP group had a more acute cranial base angle, shorter and more retruded maxillae and were more skeletal III than the subjects in the Control group. In the UCLP group, the upper and lower incisors were less proclined than in the Control group, the interincisal angle was more obtuse and the overjet reduced by 6 mm. There were no significant facial height differences. The nasolabial angle (Col-Sn-UL) was significantly more obtuse and the upper lip relative to the E line more retrusive in the UCLP group. There was no significant difference between the groups in facial heights or the maxillo-mandibular planes angle. CONCLUSION: Malay children with repaired UCLP have small, retrusive maxillae. The mandible in this group of children was of normal size and position, relative to the cranial base. Pressure from the repaired upper lip may be responsible for the retruded maxillae, retroclined incisors and obtuse nasolabial angle.

Mandibular arch orthodontic treatment stability using passive self-ligating and conventional systems in adults: A randomized controlled trial.

OBJECTIVE: This randomized controlled trial aimed to compare the stability of mandibular arch orthodontic treatment outcomes between passive self-ligating and conventional systems during 6 months of retention. METHODS: Fortyseven orthodontic patients with mild to moderate crowding malocclusions not requiring extraction were recruited based on inclusion criteria. Patients (mean age 21.58 ± 2.94 years) were randomized into two groups to receive either passive self-ligating (Damon® 3MX, n = 23) or conventional system (Gemini MBT, n = 24) orthodontic treatment. Direct measurements of the final sample comprising 20 study models per group were performed using a digital caliper at the debonding stage, and 1 month, 3 months, and 6 months after debonding. Paired t-test, independent t-test, and non-parametric test were used for statistical analysis. RESULTS: A significant increase (p < 0.01) in incisor irregularity was observed in both self-ligating and conventional system groups. A significant reduction (p < 0.01) in second interpremolar width was observed in both groups. Mandibular arch length decreased significantly (p = 0.001) in the conventional system group but not in the self-ligating system group. A similar pattern of stability was observed for intercanine width, first interpremolar width, intermolar width, and arch depth throughout the 6-month retention period after debonding. Comparison of incisor irregularity and arch dimension changes between self-ligating system and conventional system groups during the 6 months were non-significant. CONCLUSIONS: The stability of treatment outcomes for mild to moderate crowding malocclusions was similar between the self-ligating system and conventional system during the first 6 months of retention.

Randomized controlled clinical trial of oral health-related quality of life in patients wearing conventional and self-ligating brackets.

OBJECTIVE: The aim of this randomized controlled clinical trial was to compare oral health-related quality of life (OHRQoL) of patients treated with conventional, active self-ligating (ASL), and passive self-ligating (PSL) brackets in different therapeutic phases. METHODS: Sixty patients (mean age 18.3 years; 29 males and 31 females) requiring orthodontic treatment were randomly and equally assigned to receive conventional (Victory Series), ASL (In-Ovation R), or PSL (Damon 3MX) brackets. OHRQoL was measured with a self-administered modified 16-item Malaysian version of the Oral Health Impact Profile for immediate (soon after the visit) and late (just before the subsequent visit) assessments of the bonding and activation phases. Data were analyzed with the Kruskal-Wallis and chi-square tests. RESULTS: The PSL and ASL groups showed more immediate and late impacts in the bonding phase, respectively; the conventional group was affected in both the assessments. The first activation phase had similar impacts in the groups. After the second activation, the conventional group showed more immediate impacts, whereas the PSL and ASL groups had more late impacts. The commonly affected domains were "physical disability," "functional limitation," "physical pain," and "psychological discomfort." No significant differences in the prevalence and severity of immediate and late impacts on OHRQoL of the patients were noted in any therapeutic phase. CONCLUSIONS: No bracket system seems to ensure superior OHRQoL. This information could be useful for explaining the therapeutic phases, especially the initial one, and selecting the optimal bracket system based on the patient's preference.

Three-dimensional quantitative evaluation of facial morphology in adults with unilateral cleft lip and palate, and patients without clefts.

The aims of this study were to assess the quantitative values of measurements using proportion indices in the craniofacial region in patients with repaired, non-syndromic, complete unilateral cleft lip and palate (UCLP), and compare them with a control group who did not have clefts using the non-invasive systems of 3-dimensional technology. Three-dimensional measurements of the facial surfaces of 15 Malay patients who had UCLP repaired and 100 Malay control patients aged 18-25 years were analysed. The 3-dimensional images of the respondents' faces were captured using the VECTRA-3D Stereophotogrammetry System. Eleven craniofacial proportions were assessed using a combination of 18 linear measurements obtained from 21 anthropometric soft tissue landmarks. These measurements were used to produce proportion indices to find the differences in the morphological features between the groups, and assessed using the independent sample t test and z scores. There were significant differences between the groups in 7 out of 11 craniofacial proportion indices (p=0.001-0.044). Z scores of 2 indices were disproportionate. They were nasal index (which was severely supernormal) and upper lip index (which was moderately supernormal). Patients with UCLP had higher mean z scores, indicating that patients with UCLP tended to have larger faces than the control group. There were clinically important differences mainly in the nasolabial area, where the nose and the upper lip were wider, larger, or flatter in patients with UCLP.

Changes in the oral health-related quality of life 24 h following insertion of fixed orthodontic appliances.

OBJECTIVES: The objective of this study was to assess changes in the oral health-related quality of life (OHRQoL) among patients wearing fixed orthodontic appliances 24 h after insertion. MATERIALS AND METHODS: Sixty patients aged between 14 and 24 years (29 males and 31 females; mean age, 17.8 years; SD 3.1 years) were recruited from the Postgraduate Clinic, Department of Children's Dentistry and Orthodontics, Faculty of Dentistry, University of Malaya. The oral health-related quality of life (OHRQoL) was measured before treatment and 24 h after insertion of the orthodontic appliance. The instrument used to measure OHRQoL was a modified self-administered short version of Malaysian Oral Health Impact Profile (OHIP-16[M]) questionnaire. The higher the score, the poorer is the OHRQoL. RESULTS: Overall score of OHRQoL increased significantly 24 h after insertion (mean 43.5±10.9) as compared to before insertion (mean 34.1±9.2) (P<0.001). Significant changes were found for the following items: Difficulties in chewing, bad breath, difficulties in pronunciation, discomfort in eating, ulcer, pain, avoidances of eating certain foods, difficulties in cleaning, embarrassment, avoid smiling, disturbed sleep, concentration affected, difficulty carrying out daily activities, and lack of self-confidence (P<0.05). Significant changes were also found in the mean difference of OHRQoL for gender (P<0.001). CONCLUSION: OHRQoL was found to deteriorate 24 h after insertion of fixed orthodontic appliances in almost all domains, with significant changes in gender. This information can be used as "informed consent", which might increase patient's compliance as they are aware of what to expect from initial orthodontic treatment.

Comparison of arch form between ethnic Malays and Malaysian Aborigines in Peninsular Malaysia.

OBJECTIVE: To determine and compare the frequency distribution of various arch shapes in ethnic Malays and Malaysian Aborigines in Peninsular Malaysia and to investigate the morphological differences of arch form between these two ethnic groups. METHODS: We examined 120 ethnic Malay study models (60 maxillary, 60 mandibular) and 129 Malaysian Aboriginal study models (66 maxillary, 63 mandibular). We marked 18 buccal tips and incisor line angles on each model, and digitized them using 2-dimensional coordinate system. Dental arches were classified as square, ovoid, or tapered by printing the scanned images and superimposing Orthoform arch templates on them. RESULTS: The most common maxillary arch shape in both ethnic groups was ovoid, as was the most common mandibular arch shape among ethnic Malay females. The rarest arch shape was square. Chi-square tests, indicated that only the distribution of the mandibular arch shape was significantly different between groups (p = 0.040). However, when compared using independent t-tests, there was no difference in the mean value of arch width between groups. Arch shape distribution was not different between genders of either ethnic group, except for the mandibular arch of ethnic Malays. CONCLUSIONS: Ethnic Malays and Malaysian Aborigines have similar dental arch dimensions and shapes.