Siti Adibah Othman

Abstract: 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 diff erences 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: Th e 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 signifi cantly diff erent 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 diff erent 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.

Abstract: The objective of this study was to investigate the applicability of Bolton’s ratios in orthodontic population of Malaysian main ethnics; Malay, Chinese and Indians. Ninety convenient samples consisting of 30 pre-orthodontic study casts from each ethnic that fits the inclusion criteria were selected. The greatest mesiodistal widths of each tooth from six to six for overall ratio and three to three for anterior ratio were measured using a digital callipers linked to Hamilton Arch Tooth System software to the nearest 0.01mm. Means of the ratios were calculated using Bolton analysis. One sample t-test statistic analysis was carried out to compare the means with Bolton values of anterior ratio and overall ratio and one-way ANOVA was used to analyze comparison between ethnic groups of the anterior ratio and the overall ratio with the level of statistical significance set at p < 0.05. However, there were no significant differences when comparing Bolton values with Chinese and Indian anterior and overall ratios. The Bolton standards could be applied to Malaysian Chinese, Indians and Malay’s female. Subsequently, a specific standard should be used for the Malays orthodontic population.

Abstract: To investigate the craniofacial morphology of Malay children with repaired UCLP and compare the data with non-cleft Malay children. 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. 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. 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.

Abstract: The objective of this retrospective study was to investigate what percentage of the dental students in the University of Malaya has a tooth size discrepancy. The sample comprised 40 good quality pre-treatment study models with fully erupted and complete permanent dentitions from first molar to first molar, which were selected from the dental students of the University of Malaya. The mesiodistal diameter tooth sizes were randomly measured manually from first molar to first molar using digital calliper (Mitutoyu) accurate to 0.01 mm, and the Bolton analyses for anterior and overall ratios were calculated by scientific calculator. Reproducibility analysis for intra- and interexaminer calibrations was assessed by measuring 10 study models twice, a week apart. A paired sample t-test and the correlation coefficient were used to evaluate the systematic and random errors of the measurements using Statistical Package for Social Sciences (SPSS) version 12.0. The reproducibility of the intra and inter-examiners for the sum of upper and lower mesiodistal tooth size were high (average mean difference = 0.62, r = 0.82). This study found 47.5% of the samples had anterior, and about 10% had overall· tooth width ratios greater than 2 standard deviations from Bolton’s mean. Large percentage of the dental students of the University of Malaya has tooth size discrepancies outside of Bolton 2 standard deviations. It would seem prudent to routinely perform the tooth size analysis and include the findings into orthodontic treatment planning.

Abstract: OBJECTIVE: To determine and compare the reproducibility and speed of two methods of performing Bolton's tooth-size analysis. DESIGN: Analysis of randomly selected clinical sample. SETTING: Bristol Dental Hospital, University of Bristol, United Kingdom. MATERIALS AND METHODS: Pre-treatment study casts of 150 patients were selected randomly from 1100 consecutively treated Caucasian orthodontic patients. Bolton tooth-size discrepancies and ratios were measured using two methods; one method employed entirely manual measurement and the Odontorule slide rule, while the other employed digital calipers and the HATS analysis software. Twenty study casts were measured twice, a week apart with both methods. Another three investigators also measured 20 study casts twice with the HATS analysis. RESULTS: There were small or no systematic errors within or between these two methods. A very significant difference was evident for mean time measurements between the two methods (mean time for HATS was 3.5 minutes and for Odontorule was 8.9 minutes). There was relatively high error variance of both methods of measurement as a percentage of the total variance. CONCLUSIONS: On-line electronic measurement was found to be more rapid than the manual method used. Both methods demonstrate relatively high random error and this has important consequences for the clinical use of Bolton's ratios.

Abstract: To explore how many millimeters of tooth size discrepancy (TSD) are clinically significant, to determine what percentage of a representative orthodontic population has such a tooth size discrepancy, and to determine the ability of simple visual inspection to detect such a discrepancy.

Abstract: A case report of a 13-year old male presented in his mixed dentition stage with a Class II division 2 incisor relationship on a mild Class II skeletal base, complicated by an increased overbite, retroclined upper and lower incisors (bimaxillary retroclination) and moderate crowding in the upper and lower labial segments. Treatment was undertaken without extraction employing an upper removable appliance with a flat anterior bite plane to correct the overbite, and an anterior screw to proclined the upper incisors while waiting for the eruption of the permanent teeth. Pre-adjusted edgewise fixed appliances were placed in the lower arch, then in the upper arch to level and align the dentition, achieve Class I incisor relationship, reduced the interincisal angle and close residual spaces.

Abstract: OBJECTIVES: To review the literature on Bolton's tooth-size discrepancies (TSD) with specific attention to the prevalence of TSD, and the possible influence of different classes of malocclusion, gender and racial group. Also examined were the validity of the standard deviations from Bolton's samples as an indicator of significant TSD, methods of measurement of TSD and their reproducibility. Based on the review, suggestions are made as to how future work could be improved. RESULTS AND CONCLUSIONS: Studies have reported from 20 to 30% of people with significant tooth-size anterior discrepancies and 5-14% for overall TSD. Bolton's original sample was appropriate for indicating what ratio is most likely to be associated with an excellent occlusion, but was not suited to indicating the size or prevalence of significant TSD. Most studies use samples that are not likely to be representative of orthodontic patients in the UK or, indeed, elsewhere. Although some statistically significant differences have been reported, gender and racial group seem unlikely to have a clinically significant influence on Bolton's tooth-size ratios. Class III malocclusions may have larger average ratios. Computerized methods of measurement are significantly more rapid. Most studies performed or reported their error analysis poorly, obscuring the clinical usefulness of the results. Studies are needed to properly explore the reproducibility of measurement of TSD and to appropriately determine what magnitude of TSD is of clinical significance.

Abstract: The purpose of this study was to validate the use of digital dental study casts obtained from Cone beam CT Scan (CBCT) against gold standard; that is traditional dental study cast measured with digital caliper. Thirty-four study casts of Malaysian Aborigines were selected from Centre of Malaysian Pribumi Studies Databank. Palatal depth of each study casts were measured using Mitutoyo digital caliper. Subsequently, all the study models were scanned using i-CAT CBCT and the palatal depth were measured using i-CAT software. Data were analysed using SPSS version 12.0 where Intraclass correlation and paired T-test were employed. There was no significant difference in palatal depth between CBCT and Mitutoyo digital caliper (p>0.05). Average measures for Intraclass Correlation is 0.753 indicate that it is consistently good. Within the limitation of this study palatal depth measurement produced by CBCT was as accurate as the digital caliper. However, more samples and parameters should be added to further substantiate the result of this study.