Displaying all 12 publications

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  1. Rijal OM, Abdullah NA, Isa ZM, Noor NM, Tawfiq OF
    PMID: 23367155 DOI: 10.1109/EMBC.2012.6347220
    Selected landmarks from each of 47 maxillary dental casts were used to define a Cartesian-coordinate system from which the positions of selected teeth were determined on standardized digital images. The position of the i-th tooth was defined by a line of length (l(i)) joining the tooth to the origin, and the angle (θ(i)) of this line to the horizontal Cartesian axis. Four teeth, the central incisor, lateral incisor, canine and first molar were selected and their position were collectively used to represent the shape of the dental arch. A pilot study using clustering and principal component analysis strongly suggest the existence of 3 groups of arch shape. In this study, the homogeneity of the 3 groups was further investigated and confirmed by the Dunn and Davies-Bouldein validity indices. This is followed by an investigation of the probability distribution of these 3 groups. The main result of this study suggests 3 groups of multivariate (MV) normal distribution. The MV normal probability distribution of these groups may be used in further studies to investigate the issues of variation of arch shape, which is fundamental to the practice of prosthodontics and orthodontics.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  2. Al-Khatib AR, Rajion ZA, Masudi SM, Hassan R, Townsend GC
    Homo, 2013 Aug;64(4):296-311.
    PMID: 23755965 DOI: 10.1016/j.jchb.2013.04.002
    The aim of this study was to evaluate the relationships of selected facial measurements with mesio-distal crown widths and dental arch dimensions in individuals with normal occlusions. A cross-sectional study was conducted on 276 subjects with Angle's Class I normal occlusions. Three-dimensional images of the face and dental casts were captured and analyzed using stereophotogrammetric systems. Significant correlations were found between the sagittal facial variables and both upper and lower dental arch dimensions and to lesser degree with the horizontal and vertical variables. The values of correlation coefficients calculated between facial and dental crown measurements ranged from .01 to .50 for upper teeth and .01 to .49 for lower teeth. The values of correlation coefficients between facial and upper dental arch dimensions ranged from .01 to .55 and those between facial and lower dental arch dimensions ranged from .01 to .60. A principal components analysis showed that the sagittal dimensions, face height, nose, labial fissure, binocular widths were positively associated with dental arch dimensions and mesio-distal crown diameters in males. On the other hand, only the sagittal variables were associated with dental dimensions in females. The results of this study confirm that positive associations exist between facial and dental arch dimensions. These relationships should be taken into consideration when attempts are made to modify dental arch size as part of orthodontic treatment. Moreover, these relationships are also relevant to prosthodontists involved with selecting tooth sizes that display optimal functional balance with the craniofacial structures.
    Matched MeSH terms: Dental Arch/anatomy & histology
  3. Al-Khatib AR, Rajion ZA, Masudi SM, Hassan R, Townsend GC
    Aust Orthod J, 2012 May;28(1):22-9.
    PMID: 22866590
    The development of three-dimensional computer imaging has many applications in dentistry, including the analysis of dental casts.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  4. Wey MC, Shim CN, Lee MY, Jamaluddin M, Ngeow WC
    Aust Orthod J, 2012 May;28(1):17-21.
    PMID: 22866589
    This study aimed to establish a safety zone for the placement of mini-implants in the buccal surface between the second maxillary premolar (PM2) and first maxillary molar (M1) of Mongoloids.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  5. Hussein KW, Rajion ZA, Hassan R, Noor SN
    Aust Orthod J, 2009 Nov;25(2):163-8.
    PMID: 20043553
    To compare the mesio-distal tooth sizes and dental arch dimensions in Malay boys and girls with Class I, Class II and Class III malocclusions.
    Matched MeSH terms: Dental Arch/anatomy & histology
  6. Wan Hassan WN, Othman SA, Chan CS, Ahmad R, Ali SN, Abd Rohim A
    Am J Orthod Dentofacial Orthop, 2016 Nov;150(5):886-895.
    PMID: 27871715 DOI: 10.1016/j.ajodo.2016.04.021
    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.

    Matched MeSH terms: Dental Arch/anatomy & histology
  7. Dung TM, Ngoc VTN, Hiep NH, Khoi TD, Xiem VV, Chu-Dinh T, et al.
    Sci Rep, 2019 02 28;9(1):3101.
    PMID: 30816230 DOI: 10.1038/s41598-019-39710-4
    This study aimed to define the width and length of the dental arch in 12-year-old Vietnamese children, and to elucidate differences between genders and among ethnic groups. A cross-sectional study was conducted in 4565 12 years-old children from the 4 major ethnic groups in Vietnam (Kinh, Muong, Thai, and Tay), with a healthy and full set of 28 permanent teeth that had never had any orthodontic treatment and with no reconstructive materials at the measured points. The mean variables in all subjects were 36.39 mm for upper inter-canine width; 46.88 mm for upper inter-first molar width; 59.43 mm for upper inter-second molar width; 10.41 mm for upper anterior length; 32.15 mm for upper posterior length 1; 45.52 mm for upper posterior length 2; 28.31 mm for lower inter-canine width; 41.63 mm for lower inter-first molar width; 54.57 mm for lower inter-second molar width (LM2W); 7.06 mm for lower anterior length (LAL); 26.87 mm for lower posterior length 1 (LP1L); and 41.29 mm for lower posterior length 2. Significant differences in these parameters between genders were found in all ethnic groups, except for LAL in the Kinh and Thai groups, and LP1L in the Tay group. Significant ethnic differences were also found in almost all parameters except LM2W in both males and females. Taken together, the representative sizes of dental arches of 12-year-old Vietnamese children have been defined. Our data indicate that there are some variations in dental arch dimensions among ethnic groups and between genders.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  8. Zabidin N, Mohamed AM, Zaharim A, Marizan Nor M, Rosli TI
    Int Orthod, 2018 03;16(1):133-143.
    PMID: 29478934 DOI: 10.1016/j.ortho.2018.01.009
    OBJECTIVES: To evaluate the relationship between human evaluation of the dental-arch form, to complete a mathematical analysis via two different methods in quantifying the arch form, and to establish agreement with the fourth-order polynomial equation.

    MATERIALS AND METHODS: This study included 64 sets of digitised maxilla and mandible dental casts obtained from a sample of dental arch with normal occlusion. For human evaluation, a convenient sample of orthodontic practitioners ranked the photo images of dental cast from the most tapered to the less tapered (square). In the mathematical analysis, dental arches were interpolated using the fourth-order polynomial equation with millimetric acetate paper and AutoCAD software. Finally, the relations between human evaluation and mathematical objective analyses were evaluated.

    RESULTS: Human evaluations were found to be generally in agreement, but only at the extremes of tapered and square arch forms; this indicated general human error and observer bias. The two methods used to plot the arch form were comparable.

    CONCLUSION: The use of fourth-order polynomial equation may be facilitative in obtaining a smooth curve, which can produce a template for individual arch that represents all potential tooth positions for the dental arch.

    Matched MeSH terms: Dental Arch/anatomy & histology*
  9. Rijal OM, Abdullah NA, Isa ZM, Davaei FA, Noor NM, Tawfiq OF
    PMID: 22255484 DOI: 10.1109/IEMBS.2011.6091261
    Standardized digital images of maxillary dental casts of 47 subjects were analyzed using MATLAB software whereby the two hamular notches and the incisive papilla defines the Cartesian vertical and horizontal axes, as well as the origin. The angle and length of the midpoints of the anterior teeth, mesiobuccal and distobuccal cusp of the posterior teeth were measured from the origin and denoted as θ(1), …, θ(18) and l(1), …, l(18) respectively. These values were collectively used to represent the shape of each dental cast. Clustering and principal component analyses were employed to find possible groups of dental arches using the above measure of shape. The main result of this study is that the 3 groups of dental arch shape may be represented by the novel feature vector v(k) = (θ(k)(1), l(k)(1), θ(k)(3), l(k)(3), θ(k)(5), l(k)(5), θ(k)(13), l(k)(13)), k = 1, 2, 3. Knowledge of v(k) implies three impression trays should be sufficient in a particular prosthetic dentistry application for Malaysian patients. Further, given that v(k) are accurately measured they may be potential candidates as evidence in specific application of forensic dentistry.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  10. Purmal K, Alam MK, Moganadass DD, Zakariat NN, Cheong NW
    Aust Orthod J, 2013 May;29(1):34-42.
    PMID: 23785936
    To assess the applicability of Pont's Index in a Malaysian population by obtaining baseline measurements of dental arch shape based on premolar arch width, molar arch width and the combined width of the maxillary incisors. A secondary aim was to determine whether a correlation exists between arch widths, Pont's Index and the facial framework.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  11. Al-Khatib AR, Rajion ZA, Masudi SM, Hassan R, Anderson PJ, Townsend GC
    Orthod Craniofac Res, 2011 Nov;14(4):243-53.
    PMID: 22008304 DOI: 10.1111/j.1601-6343.2011.01529.x
    To investigate tooth size and dental arch dimensions in Malays using a stereophotogrammetric system.
    Matched MeSH terms: Dental Arch/anatomy & histology*
  12. Keng SB, Foong KW
    Int Dent J, 1996 Apr;46(2):103-7.
    PMID: 8930682
    In the absence of pre-extraction records, investigators have used various methods to aid in the selection and placement of artificial teeth for complete dentures. Natural tooth position and size provide the dentist with an optimal guide. A study was conducted on a group of ethnic Chinese subjects where direct measurements were made of the arch size and width of the maxillary central incisor on stone casts. The anterior arch width represented by the inter-canine cusp tip distance was 35.74 +/- 2.17mm. The mesiodistal diameter of the maxillary central incisor was 8.85 +/- 0.59mm with a range of 7.60mm to 11.20mm. The results of this study was discussed against other findings on the Caucasian, Nigerian and Malay groups. The significance of artificial tooth selection for dentures was highlighted in relation to the results obtained from the study for the group of Chinese and other races.
    Matched MeSH terms: Dental Arch/anatomy & histology*
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