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Objectives There is a disparity between males and females when it comes to size and appearance. In forensic and anthropological investigations, it is crucial to identify an unknown individual's gender, and it is possible to discern individual differences based on differences in dental features among populations. For identifying individuals, tooth dimensions are an effective, simple, and low-cost means of determining sex. Based on dental casts, this study aims to assess sexual dimorphism among four ethnic tribes of Northeast India using the mesiodistal (MD) dimension of canines and arch perimeter (AP) of the upper and lower jaws. Methods In each of the four ethnic groups studied, 50 males and 50 females with dental casts were measured in millimetres for the MD dimension of canines and AP of the upper and lower jaws. SPSS version 20 (IBM Corp., Armonk, NY) was used to analyze the data based on Student's t-test, considering a p-value of <0.05 as significant. Results Males had significantly larger MD dimensions of canines in the maxillary and mandibular jaws (p-value<0.05). The AP of both maxilla and mandible are higher in males than females in all four ethnic groups. However, the difference between the two genders for the AP of the maxilla is statistically significant only in Meitei and Singpho groups (p-value<0.05). In the case of the mandibular jaw, the AP was significantly lower in females in all four ethnic groups (p-value<0.05). Conclusion Significant sexual dimorphism exists among the individuals in the four ethnic group populations. The MD dimension and AP are essential to establish sexual dimorphism among populations. The MD dimension of the maxillary and mandibular canine and AP showed significant sexual dimorphism in the present study among all four ethnic groups.

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(1) Background: Accurate diagnosis and treatment plans in orthodontics were facilitated by novel technologies. The prediction of occlusal problems is of utmost importance for clinicians. This present study aimed to find any possible correlation between unilateral and bilateral palatally impacted maxillary canine, palatal dimensions, and maxillary arch perimeter using digital measurements and determine the factors that could be used as predictors for maxillary palatal canine impaction. (2) Method: A cross-sectional study was conducted on cone-beam computed tomography images of orthodontic patients aged 15 to 25. Palatal dimensions and maxillary arch perimeter were digitally measured using Materialize Interactive Medical Image Control System. (3) Results: A significant difference was found between the case and the study groups regarding palatal depth, length, and arch perimeter, except for the palatal width. A weak correlation was reported in palatal depth and length with canine impaction, whereas the correlation was moderate concerning the arch perimeter. They can be used as predictors for palatal canine impaction. (4) Conclusion: Palatal dimensions and dental arch perimeter affect maxillary palatal canine impaction. Deficient arch perimeter, palatal depth, and length could be helpful in the prediction of maxillary palatal canine impaction.

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OBJECTIVES: To investigate the effects of long-term use of the lower lingual arch (LLA) on the sagittal and vertical positions of the permanent lower incisors and first molars. MATERIALS AND METHODS: The sample consisted of 98 patients who were treated with an LLA (LLA group) and 39 patients who were treated without an LLA (no-LLA group). The positional changes of the lower incisors and first molars were analyzed after performing mandibular structural superimpositions on lateral cephalometric radiographs taken before treatment (T1) and at the end of LLA therapy (T2). The mean ages at T1 and T2 were 8.5 years and 13.2 years, respectively. Study casts were analyzed to quantify arch dimensional changes. RESULTS: Mesial movement of the lower molar cusp was similar between the LLA and no-LLA groups, but the vertical position was slightly greater at T2 in the LLA group. In the LLA group, there was a molar tip-back effect, and the lower incisors were proclined 4.2° more than in the no-LLA group. Arch perimeter decreased 3.6 ± 2.6 mm without an LLA and 0.97 ± 3.7 mm with an LLA. Intercanine and intermolar widths both increased about 1 mm more with an LLA (P < .0001). CONCLUSIONS: The LLA does not seem to restrict mesial movement and vertical eruption of the lower incisors and molars in the long term. The LLA effectively preserves the arch perimeter at the expense of a slight lower incisor proclination.

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AIM: The objectives are to compare the extent and to find whether it is arch dimension or tooth size that contributes to a greater extent to malocclusions such as dental crowding and proclination. MATERIALS AND METHODS: A total of 90 pretreatment models were selected and divided into three groups, namely uncrowded (Group-A), crowded (Group B), and proclination (Group-C). Measurements obtained were: (1) The largest mesiodistal width of each tooth on each arch (except the second and third molars), (2) Buccal inter-canine and inter-molar widths, (3) Lingual inter-canine and inter-molar widths, (4) Arch perimeters, and (5) Arch length. RESULTS: The mesiodistal teeth dimensions were higher in crowded and proclination group. Both inter canine width and inter molar width of maxilla were reduced in crowded group. Maxillary and mandibular arch perimeter and arch lengths were higher proclination group.

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Hard palate is regarded as an important part of the human skull, which contributes to the separation of the oral and nasal cavities. The aims of the study were to investigate the morphology of the hard palate in order to create a general guideline of three-dimensional values of the palate in a Kurdish sample in the city of Sulaimani as well as determining the possible correlations between different palatal parameters in class I malocclusion with the maxillary arch form and perimeter. A retrospective study design was adopted by collecting 100 study models of orthodontic patients aged 16-24 years old attending different private dental clinics in the city of Sulaimani seeking orthodontic management. In this study, three-dimensional palatal measurements including depth, length, and width were measured in an attempt to discover their correlation with each maxillary arch form and perimeter. Additionally, measurements of inter-molar width, inter-canine width, and arch perimeter were carried out. About two-thirds of those seeking orthodontic treatment were females. Nearly 80% of the study sample had narrow palate followed by 15 and 5% of intermediate palate and broad palate, respectively. In regard to arch form, almost 90% of subjects were with tapered maxillary arch form and 10% of them with oval arch form. Males had increased dimensions compared to females, with significant differences, except in palatal depth in the molar area, and palatine height index, in which females showed increased dimensions than males but the differences were statistically non-significant. A strong positive correlation was observed between arch form and canine depth. In regard to arch perimeter, a strong negative correlation was found with molar depth and a medium positive correlation with each of canine depth, palatal width, and palatal length.

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OBJECTIVES: To investigate the association between the management of mandibular arch perimeter during development of the dentition and its effects on second permanent molar (M2) eruption. MATERIALS AND METHODS: Seven electronic databases were searched without restrictions up to June 2020. Assessment was performed using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool for non-randomized clinical trials (non-RCT). Odds ratio (OR) with 95% confidence intervals was calculated from random-effects meta-analyses. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool was used to assess the certainty of the evidence. RESULTS: Five non-RCTs, with serious to moderate risk of bias, were included. A low certainty of evidence indicated that individuals undergoing mandibular arch perimeter management by controlling the position of the first molar had a high prevalence of M2 eruption difficulties. The odds of eruption disorders was 7.5 times higher (OR: 7.57, [3.72, 15.41], P < .001) in treated individuals. Subgroup analysis revealed that appliances that increased the arch perimeter lead to a greater chance of eruption disorders compared to appliances that only maintained the perimeter. The predictive factors for the M2 eruption difficulty were its previous mesioangulation in relation to the first molar (>24°) and the treatment time (>2 years). CONCLUSIONS: Mandibular arch perimeter management during development of the dentition leads to an increase in the occurrence of M2 eruption difficulties. The identification of possible risk factors as well as the choice of the appropriate appliance type and the monitoring of these individuals seems to be essential to avoid undesirable effects with this therapy.

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INTRODUCTION: Forensic dentistry is an evolving field in legal medicine. In mass disasters, the co-mingled body parts can be misplaced; however, the intervention by dental experts can efficiently sort out the dispute. Understanding the fact that, rule of phi applies to all that exists in nature, in the present study, we aimed to correlate the Total Maxillary Arch Perimeter with the Total Body Height of an individual in cases scenarios where only the skull along with maxilla is the only leftover remains of the unidentified. MATERIAL AND METHODS: An observational study was designed involving ninety subjects comprising 45 males and 45 females of age 25 to 30 years for the following parameters. Total Body Height (TBH) was measured in centimetres using anthropometric rod. Total Facial Height (TFH) was then measured from nasion to gnathion using digital vernier caliper. Total Maxillary Arch Perimeter (TMAP) was measured from the maxillary arch model cast using digital vernier caliper. RESULTS: The Total Maxillary Arch perimeter has significant positive correlation with Total Body Height as well as Total Facial Height of an individual. The regression equation was positively established for the prediction of Total Body Height from the known Total Maxillary Arch Perimeter as Total Body Height = 80.91762 + 0.718777 (Total Maxillary Arch Perimeter). CONCLUSION: The Total Maxillary Arch Perimeter can be used as a predictive tool in estimating the Total Body Height of the individual where the skeletal remains of the skull along with maxilla is only present.

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Every practicing orthodontist today is aware of the importance of considering arch form in the attainment of a functional orthodontic correction [1]. Arch perimeter or circumference prediction is an essential component when Tooth Size Arch Length Discrepancy (TSALD) is estimated. Arch perimeter is the distance from mesial contact of the permanent molar on one side to the mesial contact of the permanent molar on the other side, with the line connecting the buccal/incisor tip points in the intervening teeth. This is most evident when seeking to resolve dental crowding or arch-length discrepancy (ALD) [2]. The shape of the arch form of maxillary and mandible resembles that of the various geometric forms such as including ellipse, parabola, hyperbola, and catenary curve [3], [4], [5], [6]. Ellipse is the best form that fits the shape of the Maxillary arch [1,2]. The mathematical equation formulated by Srinivasan Ramanujan in 1914 for widely considered to be the most accurate for calculation of the circumference of an ellipse is [7]. The computation of the circumference of the ellipse by this equation requires two values- 'a' and 'b,' the semi-major and semi-minor axis [half of the major axis and minor axis of the ellipse] respectively [8]. The perimeter (P) of an ellipse is given by the formulae; = π(a+b){1+(3h/(10-√(4-3h))}; where h=(a-b)2/(a+b)2 and calculated Maxillary arch perimeter (CP) =1/2 P. This necessitates a complex series of steps, and to overcome this, a statistical formula is developed by algorithm steps for mathematical equation where perimeter can be directly obtained by just two inputs 'a' and 'b' in excel sheet. We correlated this calculated arch perimeter (CP) with directly measured perimeter (MP) and marginal difference estimated in three different classes of malocclusion.

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PURPOSE: Dental arch length, width, and perimeter are considered to be important for the diagnosis and treatment of orthodontic cases. This study aimed to utilize dental arch width and length to create an equation for predicting dental arch perimeter. MATERIALS AND METHODS: Sixty-seven pairs of study models for patients with normal occlusion who received dental treatment were included in this study. Dental arch width at the level of the canines, first premolars, and first molars, in addition to dental arch length and perimeter, were measured using a digital vernier with 0.01mm accuracy. Data were subjected to step-wise regression analysis to determine the major predictors of arch perimeters and develop regression equations for both arches. The predicted arch perimeters were compared with the actual measured values using paired sample t-test. RESULTS: For both arches, the perimeter showed a direct, moderate to strong, highly significant correlation with the length and width measurements. Findings from step-wise regression analysis indicated that there was a strong correlation between arch perimeter and the inter-canine width and arch length, which explained 67.7% of the variation in arch perimeter in the maxillary arch. In the mandibular arch, inter-molar width, inter-canine width, and arch length explained 55.1% of the variation in the dental arch perimeter. The arch perimeter values predicted from the developed equations were not significantly different from the actual values that were measured. CONCLUSION: New regression equations based on dental arch width and length at the level of the premolars, molars, and canines were developed to predict dental arch perimeters for both the mandibular and maxillary arches.

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Objective@# By analyzing changes of dental arch width and length during the aligning and leveling period (non-extraction case) with two kinds of self-locking bracket, compare the difference between the active self-locking bracket with the passive bracket.@*Methods@#The data of dental arch perimeter change amount and dental arch width and length change amount (WU/L3, WU/L4, WU/L5, WU/L6, U/LL) were statistically analyzed using the correlation and regression method by comparing active and passive brackets for the correction of dental arch variations. Two different brackets for the correction of the measured values of the dental arch variations was analyzed by t-test. Results There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Results @#There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Conclusin @#Active and passive self-locking bracket have good arch expansion effecting. The active self-locking bracket is slightly dominant than the passive bracket in the expansion of the canine width whereas the active self-locking bracket is better than the passive in the expansion of the mandibular first molar and arch perimeter which should be widely applied to the appropriate cases.

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The dental arch perimeter and transpalatal width are the most significant arch dimensions in the developing individuals. Its management during the primary, mixed and early permanent dentition are greatly important for the normal development of the dental arches and significantly improve the occlusion in adulthood. Malocclusion is a constant source of threat to the facial appearance. Severe anterior crowding and narrow maxillary arches adversely affect the smile, facial profile and consequently patient becomes handicapped socially as well as psychologically. Maxillary expansion has been used in resolving the problems of crowding, constricted arches and allow for forward growth of the mandible in growing children. This case report describes the use of a customized modified Haas appliance in intercepting the maxillary anterior crowding and gain the transpalatal width and arch perimeter of the maxilla, enhance the smile and facial profile and to allow the forward mandibular growth without any anterior occlusal interferences.

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OBJECTIVE: To investigate the maxillary and mandibular anterior crown width/height ratio and its relation to various arch perimeters, arch length, and arch width (intercanine, interpremolar, and intermolar) groups. MATERIALS AND METHODS: The calculated sample size was 128 subjects. The crown width/height, arch length, arch perimeter, and arch width of the maxilla and mandible were obtained via digital calliper (Mitutoyo, Japan). A total of 4325 variables were measured. The sex differences in the crown width and height were evaluated. Analysis of variance was applied to evaluate the differences between arch length, arch perimeter, and arch width groups. RESULTS: Males had significantly larger mean values for crown width and height than females (P ≤ 0.05) for maxillary and mandibular arches, both. There were no significant differences observed for the crown width/height ratio in various arch length, arch perimeter, and arch width (intercanine, interpremolar, and intermolar) groups (P ≤ 0.05) in maxilla and mandible, both. CONCLUSIONS: Our results indicate sexual disparities in the crown width and height. Crown width and height has no significant relation to various arch length, arch perimeter, and arch width groups of maxilla and mandible. Thus, it may be helpful for orthodontic and prosthodontic case investigations and comprehensive management.

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OBJETIVO: determinar o perímetro de arco adicional necessário para o nivelamento da curva de Spee através de uma técnica laboratorial em modelos de estudo. MÉTODOS: foram utilizados 70 modelos inferiores nos quais se mediu a profundidade da curva de Spee e o perímetro do arco (de segundo molar a segundo molar). Nos mesmos modelos, após a simulação do nivelamento da curva de Spee, o perímetro de arco foi novamente avaliado, mantendo sua forma e comprimento. RESULTADOS: foi confirmada a correlação entre a profundidade da curva de Spee e o perímetro de arco adicional, sendo deduzida a fórmula [Paa = 0,21 CSmax - 0,04]. CONCLUSÃO: a técnica proposta permitiu, através da avaliação do perímetro de arco com curva de Spee nivelada, a determinação do espaço disponível para o alinhamento dentário.

AIM: To determine the additional arch perimeter needed for leveling the curve of Spee by means of a laboratory technique using dental casts. METHODS: Seventy lower dental models were used for measuring the depth of the curve of Spee and assessing the arch perimeter from second molar to second molar. In these dental casts, after simulation of leveling the curve of Spee, arch perimeter was reevaluated, after maintaining its form and length. RESULTS: The correlation between the depth of the curve of Spee and the additional arch perimeter was ratified, as can be shown by the formula [Paa = 0,21 CSmax - 0,04]. CONCLUSION: The proposed technique allowed, through the assessment of the arch perimeter with the leveled curve of Spee, the determination of the space available for tooth alignment.

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Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch form, the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. -Angle classification I malocclusion with bialveolar protrusion -Extraction of 4 1st bicuspids -No tooth anomaly or prosthesis -No abnormal attrition -No ectopically erupted teeth -Angle classification I canine and molar relationship -Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.

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