Mandibular Intercanine Width Research Articles

Age-stratified assessment of orthodontic tooth movement outcomes with clear aligners

ObjectiveThis study compared the achieved tooth movement to that predicted in the preliminary simulated digital treatment plan between adults and teenagers.Materials and methodsRecords of 60 patients (30 adults; mean age: 36.6 ± 11.36 years, and 30 teenagers; mean age: 16.23 ± 2.25 years) were randomly selected. Initial and predicted models were obtained from the initial simulated treatment plan. The first model of the refinement scan was labeled as achieved. SlicerCMF software (version 3.1; https://www.slicer.org) was used to superimpose the achieved and predicted digital models over the initial ones with regional superimposition on relatively stable first molars. 600 teeth were measured in each group for horizontal, vertical, angular movements, and transverse dimensions. Accuracy was defined as the achieved amount of movement minus predicted and was calculated for each individual and compared between teens and adults.ResultsThe mandibular inter-canine width accuracy was statistically significant between groups (p = 0.050). Significant under-correction in horizontal movements was noted for mandibular first premolars in teenagers compared to adults (p = 0.037). There was considerable over-correction in horizontal movements for mandibular central and lateral incisors between groups (p < 0.05). No significant difference was observed between groups in the vertical plane. Rotations were underachieved for maxillary first premolars, more in adults than teenagers (p = 0.017).ConclusionThe accuracy of achieved versus predicted tooth movement between adults and teenagers was significant for the inter-canine width. Mandibular central and lateral incisors showed significantly greater over-correction in adults in the horizontal plane. The accuracy of rotations and vertical movements was comparable.

Mandibular Intercanine Width at Three Stages of Mixed Dentition in Children at Namakkal District: A Cross-sectional Study.

To assess and compare the mandibular intercanine width (ICW) of children at three stages of mixed dentition in children at Namakkal district. An analytical cross-sectional study was conducted among 135 schoolchildren aged 7-11 years, with 45 children in each group. Group I included children with completely erupted permanent mandibular central incisors, group II included children with completely erupted permanent mandibular central and lateral incisors, and group III included children with completely erupted permanent mandibular central incisors, lateral incisors, and canines. Impressions were made in the mandibular anterior region, and study casts were prepared. Measurements of the mandibular ICW were taken using a digital vernier caliper. The mean mandibular ICW after the complete eruption of permanent mandibular central incisors, lateral incisors, and canines was 23.7, 25.5, and 25.7 mm, respectively. There was a statistically significant difference in the ICW between the three groups (p < 0.001). Post hoc tests showed that mandibular ICW was statistically significant between groups I and II and group III (p < 0.001). Linear regression analysis showed that age does not contribute to the changes in mandibular ICW. The average mandibular ICW found can be a standard comparison for treatment planning in the western Tamil Nadu population. Mandibular ICW reaches its maximum after the eruption of permanent mandibular lateral incisors. Changes in mandibular ICW should be attributed to the eruption of permanent mandibular anterior teeth and not to the age of the child. Balaraman C, Asokan S, Pollachi Ramakrishnan GP, et al. Mandibular Intercanine Width at Three Stages of Mixed Dentition in Children at Namakkal District: A Cross-sectional Study. Int J Clin Pediatr Dent 2024;17(7):737-741.

Association of Mandibular Incisor Proclination and Mandibular Arch Widths with The Levelling of Curve of Spee

Background: In this study, we aimed to determine the changes in mandibular incisor proclination and mandibular arch widths after leveling the curve of Spee (COS). Methods: Patients included in this quasi-experimental study were scheduled for fixed orthodontic treatment with a non-extraction therapy in the mandibular arch, no posterior crowding, eruption of all mandibular teeth except third molars, no spacing and Little’s irregularity index greater than 2. The COS depth and mandibular arch widths (inter-canine and inter-molar widths) were measured on plaster casts and recorded in millimeters. Mandibular incisors inclinations were measured on a cephalometric radiograph according to the incisor mandibular plane angel (IMPA) and lower incisor to NB (L1) angle. The pre-treatment and post-treatment values were compared using paired sample T-test. Pearson correlation was used to analyze the association between COS changes and other variables. P-value &lt;0.05 was considered statistically significant. Results: A total of 58 subjects with an average age of 25.10±6.81 years participated in this study. COS depth values significantly reduced after treatment (2.34±0.78mm vs 1.75±0.56mm), (P&lt;0.001). Average IMPA and L1-NB values significantly increased following COS flattening (P&lt;0.001). Mandibular inter-canine and inter-molar widths also showed significant increase after treatment (P&lt;0.001). Pearson’s correlation revealed a significant and inverse correlation between COS changes and mandibular arch width and mandibular incisor proclination values (P&lt;0.001 for both). Patient’s age and gender did not have a significant effect on COS depth. Conclusion: Flattening of COS leads to an increase in lower incisor proclination and mandibular arch width.

Relationship between dental arch width and vertical facial morphology in untreated Indian population

Introduction: Facial growth pattern is an important factor in planning orthodontic treatment properly. Knowledge of arch forms is important for an orthodontist, as it is related to future treatment outcome. Factors such as age, sex, and ethnicity are also important. The purpose of present study was to evaluate the dental arch dimensions in a different facial pattern in regional population, to evaluate correlation in the facial pattern with dental arch width to evaluate the differences in dental arch width between male and female subjects. Materials: The present study was conducted on 120 untreated subjects comprising of 60 males and 60 females aged between 16 to 38 years. The Jarabak’s ratio (posterior facial height/anterior facial height) was measured on cephalograms of each patient. Maxillary and mandibular inter-canine, first inter-premolar, second inter-premolar and first inter-molar widths were measured on study models of each patient. Results: There was no significant correlation between dental arch width and vertical facial pattern in regional population. In males, arch width is greater in canine, premolar and molar region than females. Conclusion: It was concluded that dental arch width is not associated with the vertical facial pattern but it is associated with gender. Thus, using individualized arch wires according to gender is suggested during orthodontic treatment. Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S26-S31

A comparative evaluation of pre-treatment and post-treatment outcomes in patients subjected to lower incisor extraction

Mandibular incisor crowding is the most frequently occurring characteristic of malocclusion, which can be resolved by removing single lower incisor. The aim of this study was to evaluate and compare the pre- and post-treatment outcomes through model and cephalometric analysis of the patients subjected to single lower incisor extraction. In this retrospective study pre- and post-treatment lateral cephalograms and models of 23 patients who underwent fixed orthodontic treatment with single incisor extraction on lower arch were evaluated. The study subjects were classified into two groups based on extraction pattern (Group I: Upper premolar and lower single incisor extraction; Group II: Upper non extraction and lower single incisor extraction). Both cephalometric and model analysis were carried out using Ilexis FACAD AB-2014 Version3.8.0.0 (Ilexis AB, Sweden). Wilcoxon Signed Rank test was used to compare the pre and post-treatment quantitative parameters. A significant decrease was observed in the maxillary intermolar width, mandibular intercanine width, mandibular intermolar width, mandibular arch length and anterior Bolton’s ratio. Group I subjects revealed a greater decrease in maxillary intermolar width compared to Group II, whereas a greater decrease in mandibular intercanine width, mandibular intermolar width and anterior Bolton’s ratio was documented in Group II subjects compared to Group I. Cephalometric analysis revealed significant proclination and extrusion effect of lower incisors along with protrusive tendency of the lower lip. The findings of the present study provide an additional option of extracting single lower incisor, in borderline or Class II camouflage treatment cases.

Extraction vs nonextraction orthodontic treatment: a systematic review and meta-analysis.

To compare four first premolar extraction and nonextraction treatment effects on intra-arch width, profile, treatment duration, occlusal outcomes, smile aesthetics and stability. An electronic search of the literature to June 2, 2023 was conducted using health science databases, with additional search of gray literature, unpublished material, and hand searching, for studies reporting nonsurgical patients with fixed appliances regarding sixteen sub-outcomes. Data extraction used customized forms, quality assessed with ROBINS-I (Risk Of Bias In Non-randomized Studies-of Interventions) and Cochrane RoB 2 (risk-of-bias) tool. GRADE (Grading of Recommendations Assessment, Development and Evaluation) assessed certainty of evidence. Thirty (29 retrospective studies, 1 randomized controlled trial) studies were included. Random-effect meta-analysis (95% CI) demonstrated maxillary (MD: -2.03 mm; [-2.97, -1.09]; P < .0001) and mandibular inter-first molar width decrease (MD: -2.00 mm; [-2.71, -1.30]; P < .00001) with four first premolar extraction; mandibular intercanine width increase (MD: 0.68 mm; [0.36, 0.99]; P < .0001) and shorter treatment duration (MD: 0.36 years; [0.10, 0.62]; P = .007) in the nonextraction group. Narrative synthesis included three and five studies for upper and lower lip-E plane, respectively. For American Board of Orthodontics Objective Grading System and maxillary/mandibular anterior alignment (Little's irregularity index), each included two studies with inconclusive evidence. There were no eligible studies for UK Peer Assessment Rating (PAR) score. Class I subgroup/sensitivity analyses favored the same results. Prediction interval indicated no significant difference for all outcomes. Four first premolar extraction results in maxillary and mandibular inter-first molar width decrease and retraction of upper/lower lips. Nonextraction treatment results in mandibular intercanine width increase and shorter treatment duration. There was no significant difference between the two groups regarding maxillary intercanine width, US PAR score, and posttreatment smile esthetics. Further high-quality focused research is recommended.

Heritability of dental arches and occlusal characteristics: a systematic review and meta-analysis.

The genetic basis of dentoalveolar characteristics has been investigated by several studies, however, the findings are equivocal. The objective of this systematic review and meta-analysis was to evaluate the heritability of dental arches and occlusal parameters in different stages of human dentition. Electronic databases PubMed, Embase, Scopus, Web of Science, and Dentistry and Oral Science Source were searched up to August 2023 without the restriction of language or publication date. Empirical studies investigating the heritability of dentoalveolar parameters among twins and siblings were included in the review. Study selection, data extraction, and risk of bias assessment were performed independently and in duplicate by two authors and a third author resolved conflicts if needed. Joanna Briggs Institute's critical appraisal tool was used to evaluate the risk of bias among studies and the certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria. Twenty-eight studies were included in the systematic review, of which 15 studies reporting heritability coefficients in the permanent dentition stages were deemed suitable for the meta-analysis. Random-effects meta-analyses showed high heritability estimates for maxillary intermolar width (0.52), maxillary intercanine width (0.54), mandibular intermolar width (0.55), mandibular intercanine width (0.55), maxillary arch length (0.76), mandibular arch length (0.57), and palatal depth (0.56). The heritability estimates for the occlusal parameters varied considerably, with relatively moderate values for crossbite (0.46) and overbite (0.44) and low values for buccal segment relationship (0.32), overjet (0.22), and rotation and displacement of teeth (0.16). However, the certainty of evidence for most of the outcomes was low according to the GRADE criteria. Based on the available evidence, it can be concluded that the dental arch dimensions have a high heritability while the occlusal parameters demonstrate a moderate to low heritability. PROSPERO (CRD42022358442).

Retention using braided bonded wires: a 2-year follow-up of the dentition and oral hygiene with predictors of relapse

Abstract Objective To assess gingival health and predictors of relapse related to braided-wire bonded retainers after the active phase of comprehensive orthodontic treatment. Materials and methods Fifty-one subjects were recruited in a prospective study of whom 42 were available for analysis after 2 years of retention (pre-therapeutic ages 11–18 years; 66% female). A rectangular wire retainer (0.027 × 0.011″) was bonded to the mandibular incisors. Little’s index of incisor irregularity; intercanine width; the accumulation of biofilm, calculus and gingivitis; and the incidence of retainer detachment, were recorded. Subjects were examined before orthodontic therapy, upon therapy completion, and after 2 years of retention. Results The incidence of retainer detachment over the 2 years was 27%. The post-treatment incidence of irregularity was 17%, and intercanine width reduction was 24%. Calculus accumulation increased significantly during retention (p &lt; 0.001) but not the extent of gingivitis. A multiple logistic regression demonstrated that an increase of mandibular intercanine width by ≥3 mm correspondingly increased the odds of relapse 14.3 times (95% confidence interval [CI], 1.1–196.1; p = 0.046). Patients presenting with retainer failure were 10 times (95% CI 1.6–62.8; p = 0.014) more likely to experience relapse. Subjects who experienced relapse had retainer failure earlier than those without relapse (19 vs. 23 months; p = 0.003). The occurence of relapse was not related to a treatment change in incisor irregularity, the duration of treatment, the age of the patient, gender nor to a change of intercanine width during retention. Conclusion Post-treatment changes in the mandibular arch incorporating bonded retainers were not large, but were common. An increase in mandibular incisor irregularity during retention is mostly related to treatment-induced intercanine width expansion. The bonded retainer often detached and increased calculus accumulation.

Tomographic evaluation of changes induced by herbst treatment - buccolingual inclination of mandibular canines and the intercanine distance

The aim of this study was to perform a three-dimensional evaluation of Herbst appliance effects on the mandibular canines.The subjects consisted of 23 Class II:1 patients (12 men, 11 women), mean age of 15.76± 1.75 years, consecutively treated with a Flip-Lock Herbst®appliance (TP Orthodontics, Inc., La Porte, IN, USA). The lower anchorage unit for the Herbst appliance consisted of two anchor bands connected by a lingual arch with 3mm distance from the incisor’s lingual surface. Treatment changes in mandibular canine inclination and mandibular intercanine width at the cusp and apex levels were evaluated by means of cone-beam computed tomography images (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtained before and after treatment with the Herbst appliance. There were no statistical differences between genders. Herbst appliance treatment did not result in any statistically significant changes for mandibular canine inclination and mandibular intercanine width. There were associations between mandibular canine inclination and mandibular intercanine width at the cusp (/r/ = 0.43 to 0.66) and apex levels (/r/ = 0.34 to 0.60). The three-dimensionalcone-beam computed tomography analysis of the mandibular canine segment revealed that the Herbst appliance with a mandibular anchorage unit distant from the incisor’s lingual surface does not change mandibular canine inclination and mandibular intercanine width significantly during treatment. However, large interindividual differences may result in undesired amount of mandibular canine anchorage loss in individual patients.

Maxillary and Mandibular Interarch Width Among Different Malocclusions

Objective: To determine the association of maxillary and mandibular interarch width among different malocclusions. Material and Methods: This cross-sectional study was done at the Department of Orthodontics of the Dr. Ishrat Ul Ibad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, during a period of one year from January 2017 to December 2017. Individuals with a Class I canine and molar relationship with minor crowding, normal growth and development, and mal-aligned upper and lower dental arches. Class II molar and canine relationship on at least one side, Class II division 1 or 2 groups, bilateral Class III molar relationship in centric occlusion, Class III permanent canine relationship with excessive negative overjet, good facial symmetry, and participants had to have all their permanent teeth present except for their third molars were included. Readings were obtained by measuring the interarch width using a vernier gauge caliper. The calibration of the vernier caliper was checked daily using the standard technique. The intercanine arch width was measured from the cusp tip of one canine to the contralateral canine. Intermolar width was assessed as the distance between the central fossae of the left and right first molars. The readings were taken by a single examiner, and the measurement was repeated three times with an interval of two minutes between each measurement to reduce the possibility of errors. To assess the reliability of the measurements, the intra-examiner reliability was determined using the intraclass correlation coefficient (ICC). The collected data was analyzed using statistical software, SPSS version 26. Results: The study examined the maxillary and mandibular interarch widths of participants with different types of malocclusions. Class I had the highest maxillary intercanine width, and Class III had the highest maxillary intermolar width. Class III had the highest mandibular intercanine and intermolar width. Class II Division 2 had the lowest intercanine and intermolar width in both arches. Significant differences were observed in the mean intermolar width in the mandibular arch between Class II Division 2 and Class III malocclusions and in the maxillary intercanine width between Class I and Class II Division 2 malocclusions. No significant difference was found in other width measurements among the different types of malocclusions. Conclusion: It has been concluded that patients with Class III malocclusion had narrower upper width measurements compared to the normal occlusion sample. Keywords: Maxillary, mandibular, interarch width, malocclusion

Assessing the relationship between the intercondylar distance and mandibular intercanine distance in orthopantomogram – A retrospective study

Background: In completely edentulous patients, it is necessary to replace the teeth with at most esthetics and comfort with less patient strain. Aim: The current retrospective study was done to find the relationship between the intercondylar distance and intercanine distance of the mandible by obtaining the ratio using an orthopantomogram (OPG) for lower anterior teeth selection in completely edentulous patients. Materials and Methods: The OPG of 500 subjects was selected randomly. The OPGs were taken using the Sirona Orthophos XG machine and exposed for 14.1 s at 64 kvp, 8 mA. Then, the intercondylar distance and mandibular intercanine distance were measured from the soft copy of the OPG using the software “Sidexis.” The required measurements were taken digitally from the OPG using the software “Sidexis” in millimeters (mm). The SPSS software version 22.0 was used for statistical analysis. Results: Pearson correlation coefficients (r) displayed a significant positive association between the intercondylar distance and intercanine distance of the mandible (r = 0.42; P = 0.0002). The correlation between intercondylar width and mandibular intercanine width was significant and positive for men (r = 0.26, P = 0.0003) but negative for women (r = −0.41, P = 0.0001). The ratio between the mean intercondylar width and the mean intercanine width was 1:4.90. Conclusion: The mandibular intercanine distance and the intercondylar distance have a positive and significant association. The ratio obtained in this study was 1:4.90 between the mandibular intercanine distance and the intercondylar distance that could be employed for the choice of mandibular anterior teeth.

Stature Prediction by Comparing Maxillary and Mandibular Intercanine Width and Intermolar Width among Tamil Nadu Population.

Background:Teeth are one of the strongest hard tissues that can resist a variety of antemortem and postmortem insults and an important evidence in the field of medicolegal and forensics. In the identification of unknown human remains of the deceased, stature estimation is a preliminary investigation. Previously, the comparison of osteometry with odontometry in stature determination has been made. Similarly, an attempt is made to estimate stature using intercanine and intermolar width which may be a forensic tool in the future.Aim and Objective:The aim of this study was to determine stature using intercanine and intermolar width in the maxillary and mandibular arches and correlating to identify highly reliable parameter among the two. Further to evaluate the usefulness of odontometry in stature determination.Materials and Methods:Subjects for the study were recruited from the outpatient department of APDCH and students of APDCH. One hundred subjects were included in the study comprising fifty males and fifty females within the age group of 17–28 years as per inclusion criteria. Digital Vernier caliper for measuring intercanine width (cusp tips on either sides) and intermolar width (central fossa of 1st molar on either sides) on the study models and standard anthropometer for measuring the height of the subject (vertex to the floor).Results:Compared to other parameters, the maxillary intercanine distance is statistically significant to P = 0.05 with correlation value of 0.06 by Pearson correlation method.Conclusion:The data collected were subjected to statistical analysis and was found that out of the four selected odontometric parameters, maxillary intercanine width with a P = of 0.032 and Pearson correlation of 0.307 in Group 1 (males) were found to show a significant correlation with height. Regression analysis was done, and regression equations were derived. The following regression equation can be used to calculate the height of an individual, Group 1 (male) −Y = B+ Ax. Y = 135.5 + 0.947X (X - maxillary inter canine width). This method of stature prediction may be of relative importance but not of absolute certainty, thereby making it an adjunct to various other methods of stature prediction. Therefore, using odontometric parameters in combination improves the predictability of estimating stature rather than a single parameter.

Multidisciplinary Evaluation of Pacifier Removal on Oro-Dentofacial Structures: A Controlled Clinical Trial.

It is well recognized that pacifier habit leads to occlusal and orofacial functional changes in children. However, the effects of the interruption of prolonged pacifier habit on the development of the dento-facial complex has not yet been fully characterized. Thus, the aim of this study was to investigate the influence of pacifier removal on aspects of oro-dentofacial morphology and function in preschool children. For that, a pacifier group (n = 28) and a control group (n = 32) of 4-year-old children with and without pacifier habit, respectively, were followed up by a group of dentists and speech therapists at baseline, 6 and 12 months after habit removal. Bite force and lip pressure were assessed using digital systems, and the evaluation of breathing and speech functions was performed using validated protocols, together with the measurements of dental casts and facial anthropometry. The Two-way mixed model ANOVA was used in data analysis. After 12 months, a decrease in malocclusion frequency was observed in pacifier group. Additionally, a change over time was observed in facial, intermolar and palate depth measurements, as well in bite and lip forces and speech function scores, increasing in both groups (p < 0.01). The upper and lower intercanine widths and breathing scores differed between groups at baseline and changed over time reducing the differences. The presence of speech distortions was more frequent in the pacifier group at baseline and decreased over time (p < 0.05). The interruption of pacifier habit improved the maxillary and mandibular intercanine widths, as well as the breathing and speech functions, overcoming the oro-dentofacial changes found.Trial Registration: This clinical trial was registered in the Brazilian Clinical Trials Registry (ReBEC; http://www.ensaiosclinicos.gov.br/), protocol no. RBR-728MJ2.

Evaluation of Mandibular Arch Width Changes following Fixed Retention in Post Orthodontic Patients - a Randomized Clinical Trial

Background: Retention is an integral phase in which teeth are maintained in their newly adapted position for which retainers are inserted. Retainers are generally of two types: removable and fixed. Fixed retainers are indicated in the mandibular arch for an indefinite period specifically in the non-extraction cases. Changes in intercanine and intermolar widths are valuable parameters to evaluate the stability. The objectives of this study were to assess and compare the mandibular intercanine and intermolar width changes following orthodontic treatment after insertion of two types of fixed lingual retainers for one year. Methods: Total 54 subjects were recruited in which two types of fixed lingual retainers were inserted in the mandibular arch randomly. Intercanine and intermolar arch widths were measured by digital caliper of 0.01 mm accuracy. Data was analyzed by using Statistical Package of Social Sciences (SPSS V-21). Chi-square and independent t tests were used to compare baseline characteristics. Intercanine and intermolar widths were assessed and compared using independent t test, p-value ≤ 0.05 is considered as statistically significant. Results: Intercanine width increased from baseline to T4 in both retainers. When mean differences of intercanine width were compared between two retainers significant differences were observed at T1, T2, T3 and T4 with significant p-values (&lt; 0.05) and increased intercanine width with multistranded stainless steel wire (MSW) retainers. Conclusion: Mandibular intercanine width increases significantly in post retention phase with multistranded stainless steel retainers. Thus, fiber reinforced composite retainers are more effective in preserving the arch width changes.

Sex Predictability by Using Mandibular Canine Index.

Canines are known for their higher resistance to trauma and pathological alterations when compared to other teeth. Among all the teeth, canines show highest sexual dimorphism. This descriptive cross-sectional study was commenced from January 2019 to April 2019 after the ethical approval from Institutional Review Committee. The maximum mesio-distal widths of right and left mandibular canines and mandibular inter-canine arch width were measured on the cast with the help of a divider and digital vernier callipers. Mandibular canine index was calculated by dividing the mesio-distal width of each mandibular canine with inter-canine arch width. Data was entered and analyzed using Statistical Package for the Social Sciences version 21. Sex predictability by using mandibular canine index in the present study showed poor sex predictability (57.5% - 62.5%). Sex determination should be done by other methods and mandibular canine index should be used cautiously in Nepalese population.

Assessment of various odontometric parameters in accuracy of sexual dimorphism

Sex identification is one of the most important procedures in the forensics. Teeth are a potential source of information in this process. This study describes sexual dimorphism in various parameters derived from the oral cavity. A total number of 200 subjects in the age range of 17 to 25 years were studied with the help of study casts to study the following parameters for sexual dimorphism- mesio-distal dimension of maxillary central incisor, maxillary first molar, mandibular canine, mandibular first molar; cervico-incisal dimension of maxillary central incisor, bucco-lingual dimensions of mandibular canine and mandibular intercanine width. Sexual dimorphism in the various parameters was assessed using statistical analysis. The p-value, specificity and sensitivity of various parameters were calculated and compared. Results showed mesiodistal diameter of upper and lower molars, cervico-incisal diameter of central incisor and canine index were most accurate parameters for determining sexual dimorphism. Keywords: Dimorphism, Intercanine width, Canine index.

Evaluation of the change in the tongue posture and in the hyoid bone position after Twin Block appliance therapy in skeletal class II subjects.

The tongue is posteriorly postured in a retrognathic mandible, and Twin Block appliance (TBA) therapy places the tongue and the hyoid bone in a favorable position to eliminate the risk of causing respiratory obstruction. The aim of this study was to evaluate the change in the tongue posture and in the hyoid bone position after TBA therapy. This cross-sectional study was conducted using the pre-functional (PF1), postfunctional (PF2) and post-treatment (PT) cephalograms of 30 growing subjects. The tongue posture at 6 distances and the hyoid bone position with 4 parameters were digitally measured using the Rogan-Delft View Pro-X® software. A digital vernier caliper was used to determine the inter-canine and inter-molar widths on the dental casts. The Wilcoxon signed-rank test was used to compare the PF1 and PF2 values, and the PF1 and PT values. The comparison of the PF1 and PF2 values showed significant differences in the tongue posture at distances 1-5. In the case of the hyoid bone, only the linear distance from the sella (S) to the most anterior point on the hyoid bone (H) - the SH distance - revealed a significant difference (p < 0.01). The change in the tongue posture and in the hyoid bone position achieved at the PF2 stage remained stable at the PT stage. Significant differences occurred in the PF1 and PF2 maxillary and mandibular inter-canine and inter-molar widths (p = 0.01 and p = 0.04, and p < 0.01 and p = 0.02), respectively. Twin Block appliance therapy resulted in the advancement of the mandible with a lowered posturing of the tongue. The hyoid bone was displaced inferiorly after TBA therapy, whereas the angular position of the hyoid bone remained unchanged.

Changes of mandibular dental arch shape during adolescence and its influence on late mandibular incisor crowding.

The aim was to analyze the changes in mandibular dental arch shape during adolescence and assess its relation to late mandibular incisor crowding. Longitudinal study included 68 orthodontically untreated subjects (49% female) and analyzed their data for the ages of 12, 15, 18 and 21 years. Measurements included anterior arch depth, intercanine, interpremolar/anterior and intermolar/posterior width, Little's Irregularity and Bolton's index and the ratio between anterior arch depth and width. Males had significantly greater posterior widths than females at any age (p < 0.05). The anterior arch depth continuously decreased (p < 0.05), while width increased after the age of 18 years. Mandibular incisor crowding increased during all investigated periods (p < 0.05). The increase of intercanine width at 12-21 years of age reduced the risk for mandibular incisor crowding in the same period by 74% (OR: 0.265: 95% CI 0.076-0.931; p = 0.045). The shape of mandibular dental arch continues to change during adolescence becoming more squared while mandibular incisor crowding increases. The increase in mandibular intercanine width reduces the risk of crowding.

A study on Arch Widths of Bangladeshi Adult Subjects with Class II -2 malocclusion compared to Normal Occlusion

Aim: To evaluate the transverse discrepancy in Class II div 2 malocclusion and normal occlusion. Also to test the hypothesis that models with class II div 2 malocclusions may have mean maxillary arch widths significantly smaller than those with normal occlusion. Thus the proposed study will generate interest among the orthodontists for further study over the transverse discrepancy of our patients and guide them to establish effective treatment strategy and their management.&#x0D; Materials and Methods : Cross sectional comparative study was carried out Department of Orthodontics &amp; Dentofacial Orthopedics of Dhaka Dental College &amp; Hospital, Dhaka with 100 sample was included in this study.&#x0D; Results: Maxillary intercanine, interfirst premolar and interfirst molar widths between normal occlusions and class II div 2 malocclusions were statistically significant.Maxillary measurements of class II div 2 malocclusion were smaller than normal occlusion. Mandibular intercanine, interfirst premolar and interfirst molar widths between Class II div 2 malocclusion and normal occlusions were statistically significant.&#x0D; Conclusion: This study helps in determining possible differences in the dental arch widths of Bangladeshi people in Class II-2 adults compared to adults with normal occlusion may be an important aid in further understanding of dentoalveolar characteristics of these conditions, as well as improving their management.&#x0D; Ban J Orthod &amp; Dentofac Orthop, April 2017; Vol-7 (1-2), P.27-30

Dental Arch Width in Children and Relationship to their Oral Habits

Aim: Objectives: To analyze variations in dental arch width in relation to oral habits. &#x0D; Materials and Methods : Cross sectional study was carried out Department of Orthodontics &amp; Dentofacial Orthopedics of Dhaka Dental College &amp; Hospital, Dhaka with a total number of 600 primary school children of 3-6 years ages of Bangladeshi population.&#x0D; Results: This study was a cross sectional study conducted among the 600 children with 3-6 years old prima- ry school children of Bangladeshi population. According to present study, bottle feeding causes significant reduction in maxillary intercanine width and mouth breathers show significant reduction of both arches.&#x0D; Conclusion: It was observed that the children who had used a bottle had a significant reduction in maxillary intercanine width. Breathing through mouth appeared to be associated with a reduction in the size of both arches. This was more significant in the maxillary intercanine , mandibular intercanine and mandibular molar widths. Therefore to prevent malocclusions, the public should be informed of the harm caused by certain oral habits, the benefits of breast-feeding, and the need to correct bad habits at early life.&#x0D; Ban J Orthod &amp; Dentofac Orthop, April 2016; Vol-7 (1-2), P.6-11