Kathiravan Purmal

Bolton tooth size ratio and its relation with arch widths, arch length and arch perimeter: A cone beam computed tomography (CBCT) study

Abstract Objective. The prime aim of the study was to measure and compare the 3D CBCT Bolton tooth size ratio in relation to the upper and lower arch widths, arch length and arch perimeter. Materials and methods. The data source was CBCT high volumetric data from the archives. Tooth size, arch widths, arch length and arch perimeter were measured in maxilla and mandibular arches. The independent t-test and ANOVA were used for statistical analyses. Results. The female Bolton anterior ratio (BAR) (78.373) and Bolton overall ratio (BOR) (93.231) show a greater tooth size ratio in comparison to male BAR (77.162) and BOR (93.124), respectively. However, no significant difference was found in the sexual comparison of all the measurements. Tooth size ratio in arch width groups also showed no significant difference. Significant discrepancies in the arch length (p < 0.05) groups and overall ratio and in the arch perimeter groups (p < 0.05 and p < 0.01) and anterior ratio were revealed. Conclusions. Tooth size ratios during orthodontic treatment for different arch length and arch perimeter groups need to be evaluated carefully.

3D Mapping of Safe and Danger Zones in the Maxilla and Mandible for the Placement of Intermaxillary Fixation Screws

Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length.

Fallibility of Pont's index in a Bangladeshi population

Abstract Purpose Numerous indices have been proposed to help the clinician decide how much maxillary expansion will be required to alleviate crowding. The aim of this study is to test the fallibility of Ponts index in a Bangladeshi population, by assessing the applicability of this index in a Bangladeshi population and to compare the results with inter gender, inter normal occlusion, class I malocclusion, class II and class III malocclusion. Materials and methods Dental casts of 220 Bangladeshi individuals, comprising 95 males and 125 females (age range, 18–24 years, mean age = 20). The records belonged to 100 subjects with normal occlusion. Sixty subject with class I malocclusion, including those who showed crowding more than 5 mm and 30 subjects each with class II and class III malocclusion. Arch widths were compared between the measured and the predicted values derived from Ponts formula. Comparative statistics were applied. Results No significant differences were detected between inter gender and inter normal occlusion and malocclusions. The average predicted inter-premolar width (39.18 ± 2.13 mm) and inter-molar widths (48.97 ± 2.65 mm) were higher than the actual measured means. The premolar index (85.82) and molar index (66.93) of the Bangladeshi were higher than the original Ponts indices. Conclusion Significant correlations were noted for inter-premolar and inter-molar width. The findings suggest that Ponts index potentially overestimate the arch expansion required to alleviate crowding.

Cone-beam computed tomography evaluation of Pont's index predictability for Malay population in orthodontics

Introduction: In orthodontic treatment, three-dimensional (3D) dental casts has a significant role in diagnosis and treatment planning. The aim of this study was to evaluate Ponts index predictability in orthodontics. Materials and Methods: Premolar arch width, molar arch width and mesiodistal width of the maxillary incisors were measured three-dimensionally to assess shape of dental arches. The data source was cone beam computed tomography (CBCT) high volumetric data acquisitions from Malay ethnic background. Arch widths were measured and recorded from 53 subjects (32 male and 21 female with the mean age, 25.81), both the maxillary and mandibular arches, to obtain CBCT high volumetric data. All measurements were obtained through CBCT Planmeca Romexis TM Software 2.3.1.R (Helsinki, Finland). Results: Ponts formula overestimated the upper and lower interpremolar distance, with mean differences of 8.35 ± 3 mm and 12.02 ± 3.20 mm, respectively. Furthermore, the formula overestimated the upper and lower intermolar distance, with mean differences of 7.87 ± 3 mm and 16.14 ± 5.86 mm, respectively. Conclusions: The results indicate that Ponts index is not practical for use with the Malaysian population since the index overestimated interpremolar and intermolar widths. This raises questions whether the index is a true predictor of arch width measurements.

Orthodontic treatment combination with auto transplantation for the management of impacted maxillary left lateral incisor and canine: an interdisciplinary approach.

Aims: For the orthodontic treatment of the complex cases, the interdisciplinary team work is of utmost importance, which leads to the predictable outcome with excellent treatment. The prime aim of this rare case report is to demonstrate the combined orthodontic-surgical-endodonticprosthodontic interdisciplinary management. Case Study Alam et al.; BJMMR, 4(3): 276-284, 2015; Article no.BJMMR.2015.449 277 Presentation of Case: This report describes the case of a 19 years old Malay male patient with the clinical problems of median diastema, mesio-buccally rotated maxillary left 1 st premolar, mild mandibular incisor crowding along with impacted maxillary left lateral incisor and canine. Discussion: With the advantages of the orthodontic fixed appliance, auto-transplantation of maxillary upper left lateral incisor and canine, the case was completed in an ideal orthodontic occlusion along with improved oral condition, masticatory function and esthetics. The treatment outcomes were due to orthodontic-surgical-endodontic-prosthodontic treatment with stable occlusion in sequels visits. Conclusion: An Interdisciplinary management achieved successful functional and esthetic results in the present case.

Shear bond strength of orthodontic buccal tubes to porcelain

Background: Bonding of molar tubes is becoming more popular in orthodontics. Occasionally, these bonding are done on posterior porcelain crowns or bridges. The purpose of this study was to evaluate the shear bond strength of buccal tubes on feldspathic porcelain crowns with two different methods. Materials and Methods: Forty porcelain right molar crowns were fabricated for this study. The crowns were randomly divided into two groups. In group 1, the crowns were etched with 9.6% hydrofluoric acid, silane coupling agent applied, coated with bonding primer and bonded with Transbond XT (3M Unitek, Monrovia, Calif). In group 2, the crowns were etched with phosphoric acid 37%, silane coupling agent applied, coated with bonding primer and bonded with Transbond XT. All the crowns were stored for 24 hours at 37°C and thermo-cycled before the shear bond test. The analysis of variance (ANOVA) was used to determine whether significant difference were present between the groups. Results: The results of the analysis of variance (F = 0.23) indicated the shear bond strength of group 1 (3.57 ± 0.87 MPa) was not significantly different (P > 0.05) from group 2 (3.46 ± 0.65 Mpa). Fishers exact test for the adhesive remnant index (ARI) revealed significant difference between both groups (P < 0.05). Eighty percent of group 1 buccal tubes failed at buccal tube/resin interface and eighty percent of group 2 mostly failed at porcelain/resin interface. Conclusion: Etching with phosphoric acid with the use of silane coupling agent would be safer and should make it easier for clinicians to clean the adhesive on the porcelain surface after debonding.