Intercanine Distance Research Articles

Accuracy of anterior denture tooth arrangements of CAD-CAM complete removable dental prostheses made with a tooth mold template

Statement of problemResearch evaluating the accuracy of anterior tooth mold templates to computer-aided design and computer-aided manufacture (CAD-CAM) fabricated complete removable dental prostheses (CRDPs) is limited. PurposeThe purpose of this in vitro study was to investigate the accuracy of the anterior denture tooth arrangement on CAD-CAM complete removable dental prostheses made with the anterior tooth mold template. Material and methodsA maxillary and mandibular edentulous model was mounted on a semiadjustable articulator to simulate a patient’s maxillary arch. Definitive impressions and jaw relation records were made as per the manufacturer’s protocol. A maxillary and mandibular anatomic measuring device was completely seated onto the edentulous models, centered on the edentulous model midline, and horizontally positioned parallel to the mandibular ridge. A medium-size anterior tooth mold template sticker was attached on the anatomic measuring device to identify the maxillary dental midline and incisal edge position and was sent to the manufacturer as the proposed tooth arrangement reference for the definitive complete removable dental prostheses. A total of 10 milled complete removable dental prostheses were generated for 2 groups by using 2 different tooth arrangement techniques. One group (n=5) used the monobloc milling technique without bonding of denture teeth, while the other group (n=5) used the bonding system for denture teeth on the milled denture base. For comparison, a camera mounted on a tripod was used for photographic documentation. Reference markers placed on the edentulous model were used to orient and measure the difference of 4 aspects of the anterior tooth arrangement: average incisal edge position, intercanine distance, midline, and clinical crown length of the left central incisor. The difference values between the tooth mold template and definitive complete removable dental prostheses were statistically analyzed by multivariate ANOVA (α=.05) and 1-sample t tests (adjusted α=.0125). ResultsOverall, statistically significant differences were found between the tooth mold template (control) and definitive complete removable dental prostheses at all measuring aspects except for the midline of the midline of the milled arrangement technique (P<.0125). In terms of the midline value, the value of the milled group did not show a significant difference compared with tooth mold template (-0.19 mm). However, the value of the bonded group indicated a significant difference of midline (0.44 mm toward to the left of the tooth mold template midline). When the complete removable dental prosthesis milled denture tooth and complete removable dental prosthesis bonded denture tooth techniques were compared, there was no difference in the tested variables between the milled and the bonded groups (P>.0125). ConclusionsThe tooth mold template did not represent an accurate position for definitive complete removable dental prostheses for either the milled or bonded techniques. The largest differences were found at the average incisal edge of the anterior teeth and the intercanine distance for both groups. However, there was overall no clinical difference between the 2 groups (milled and bonded) of CAD-CAM complete removable dental prostheses.

Estimation of Sex From Dental Arch Dimensions: An Odontometric Analysis

Sex estimation is one of the "big three" of human identification and is a vital aspect of the process of generating biological profile of unknown deceased. Anthropometric and odontometric methods that utilize measurement of distances between certain landmarks are commonly employed to differentiate between the 2 sexes. Teeth are the most robust and well-preserved parts of the human body, and studies have shown that the sex of an unknown individual can be estimated using their measurements. The present study was carried out to analyze the sex differences based on the dental arch dimensions of both the jaws in an Indian population. A proper understanding of dental arch dimensions not only help forensic odontologists in human identification, but also help dental practitioners in teeth restoration, and to quantify selection of anterior teeth in bonding of dentures. The dental arch dimensions of the canines, premolars, and the molars of both the jaws were recorded in dental casts of 307 participants. Comparison of the dental arch dimensions of males and females was done and logistic regression models were generated to estimate sex. Receiver Operating Characteristic analysis was done to find out the potential to estimate sex for all the dental arch dimensions in both the sexes. It was observed that maxillary intermolar II distance gave the best results in estimating the sex. The sexing accuracy is seen to increase as we go distally from canines to molars in each jaw; minimum for intercanine distance and maximum for distance between the 2nd molars. The sexing accuracy from dental arch dimensions was found to be between 72.7% and 86.5%. The models derived for estimation of sex from dental arch dimensions can be used in cases of skeletal remains.

Efficacy of the canine mandibular index technique with permanent dentition to estimate sex in humans

Objective: To determine the efficacy of the Mandibular Canine Index technique with permanent dentition to estimate sex in humans. Methodology: Descriptive, non-experimental cross-sectional study, where 200 plaster models of men and women were evaluated. Intercanine distances and mesiodistal diameters of the left and right canines were obtained using a digital vernier caliper with a resolution of 0.01mm. The sexual dimorphism of the right canine and the left canine was then determined. After that, the ICM averages were determined. Results: The ICM with permanent dentition obtained an efficiency of 69% to estimate the male sex and 67% of the female sex. Conclusions: The Mandibular Canine Index (CMI) technique with permanent dentition is effective for estimating sex in humans.

Correlation of intercanthal and interalar distance to intercanine distance for selection of maxillary ant. teeth

Background: Maxillofacial region’s reference points like interpupillary distance, intercanthal distance, interalar distance and bizygomatic width can significantly contribute toward reconstruction of two-dimensional (2D) facial profiles. Aim: To find correlation between intercanthal to intercanine and interalar to intercanine distance for maxillary anterior teeth selection. Methodology: This study was conducted at de’ Montmorency College of Dentistry/ Punjab Dental Hospital, Lahore from 29-08-2013 to 28-04-2014. Sampling technique was non-probability purposive. 200 subjects are estimated for correlation of intercanthal distance to intercanine distance and correlation of interalar distance to intercanine distance as r=0.302. Results: Out of 200 cases, 102(51%) were 20-40 years of age while 98(49%) were ranging between 41-60 years of age, mean±SD was calculated as 41.01±11.90 years, 135(67.5%) were male and 65(32.5%) were females, correlation among maxillary intercanine distance with other facial land marks shows the distance of intercanine was 37.26±3.91, it was 41.26±4.57 for interalar and 34.50+2.51 was recorded for intercanthal, the value of R2, the coefficient of determination, is 0.0893 for intercanine to intercanthal and 0.0018 for intercanine to interalar. Conclusion: We concluded that intercanthal distance to intercanine distance is more correlated as compared to interalar distance to intercanine distance in Pakistani population. Keywords: Maxillary anterior teeth, intercanthal distance, intercanine distance, interalar distance, correlation

Comparison of Changes in Incisors Inclination and Dental Arch Dimensions in Damon and MBT Systems Using Dolphin Software

Background: There is great controversy regarding the effect of MBT and Damon bracket systems on dental arch dimensions and incisor position. Objectives: We aimed to study the effects of two different brackets (MBT and Damon) on dental arch dimensions and incisors position after orthodontic treatment. Methods: In this retrospective study, the records of 20 patients who underwent orthodontic treatment with MBT or Damon bracket systems were studied. All patients had class I skeletal and dental malocclusion and were treated without extraction. The patients were treated either with Damon or MBT bracket systems (n = 10). Lateral cephalograms were traced using the Dolphin software to determine the position of incisors. In addition, transverse dimensions of dental arches were measured on occlusal photographs. Fishers’ exact test, independent-test, Man-Whitney, paired t-test, and Wilcoxon were used for statistical analysis. P &lt; 0.05 was set as significant. Results: There was no significant difference between the two groups regarding age, sex, and initial values of the variables studied. U1-Apog (mm), upper inter-canine, lower inter-second premolar distance showed a significant difference before and after treatment in the Damon system. However, no significant difference was observed between initial and post-treatment values in the MBT group. L1-Apog (°), IMPA (°), maxillary inter-first and second premolars, inter-canine, and mandibular inter-canine distance was higher in the Damon system after treatment compared to MBT. Changes of the upper and lower transverse dimensions of the dental arches and the incisor positional did not reveal a notable difference in the Damon and MBT systems (P &gt; 0.05). Conclusions: There was no significant difference regarding changes in dental arches and incisor positions between the Damon and MBT systems.

The impact of the primary canine premature extraction on the sagittal, vertical and transversal dimensions of the bone tissue

Relevance. The article studies the primary canine premature extraction as the cause of three-dimensional (sagittal, transversal, vertical) bone underdevelopment in the area of the extracted tooth. The research is relevant as there are insufficient data in the scientific literature on this topic and the prevalence of premature primary canine extraction for therapeutic and orthodontic indications is high.Materials and methods. The present case study developed a special technique for bone volume measurement in all planes by CBCT.Results. Several CBCTs of one patient over the period of three years were analyzed according to the suggested technique. The calculations demonstrated significant sagittal and vertical bone loss.Conclusions. The results of the research allowed us to conclude that premature extraction of the primary canines leads to the significant sagittal and vertical bone loss. Besides, no increase in the intercanine distance was detected despite the patient’s growth spurt.

Sexual dimorphism applying the mandibular canine index in a Brazilian sample: a pilot study

The aim of this study was to apply the morphometric quantification of the canine index for sexual dimorphism in a Brazilian sample. The sample consisted of 90 participants (45 males and 45 females) aged between 18 and 35 years. With the aid of a digital caliper, the intraoral mesio-distal measurement of the permanent mandibular right canine (MD43) and the intercanine distance (IC) were taken by three examiners. The measurements were used in a formula established by Rao, Rao, Pai e Kotian (1989) to estimate sex based on morphometric features of the human canines. The applicability of this approach for sexual dimorphism was assessed based on the inherent mandibular canine index (MCI) calculated by the formula. The MCI was higher in males than females. The mean general accuracy rate of the MCI for sexual dimorphism in the total sample was 52.22%. In males, the MCI was able to properly distinguish sex in 82.22% of the sample, while in females the accuracy decreased to 22.22%. These outcomes raise the attention for the careful use of the MCI in practice – especially in the field of Forensic Anthropology. In particular, the accuracy of the method was close to random in a sample that contained both sexes. Thus, MCI should not be used as the only tool for sexual dimorphism.

Stereophotogrammetry to evaluate young adults with and without cleft lip and palate after orthodontic and restorative treatment

Statement of problemPatients with cleft lip and palate generally present with lateral incisor agenesis, which may be treated with an implant-supported prosthesis. However, whether implants can stabilize the dental arches in patients with cleft lip and palate is unclear. PurposeThe purpose of this retrospective clinical study was to analyze the stability of the maxillary dental arch after orthodontic treatment and oral rehabilitation in the cleft area with an implant-supported prosthesis or a fixed partial denture. Material and methodsFifty-five participants, 20 with unilateral cleft lip and palate rehabilitated with implants (CLPI), 15 with unilateral cleft lip and palate rehabilitated with fixed partial dentures (CLPFP), and 20 in the noncleft group (NCLP) and their gypsum casts (N=110) were digitized and evaluated through 3D stereophotogrammetry. Measurements were made on casts obtained immediately after the orthodontic treatment (T1); for the cleft lip and palate group, casts were made 1 year after implant-supported restoration placement (T2), and for the noncleft group, 1 year after the conclusion of the orthodontic treatment (T2). The dimensions of the dental arches were measured digitally. Formula Δ=T2-T1 evaluated the stability of dental arches for intercanine distances, intermolar distances, arch length, palate surface, and volume (3D). Stability (Δ) was compared through 1-way ANOVA in all groups (α=.05). ResultsA statistically significant difference was found in the stability of the CLPI and CLPFP groups for intercanine measurement (P=.002). For the intermolar measurement, a statistically significant difference was detected between the CLPFP and NCLP groups (P=.002). From the 3D measurements, the stability was similar in all groups. ConclusionsIn patients with clefts, a fixed partial denture may provide better stability of the orthodontic outcomes than an implant-supported prosthesis. However, greater instability occurred at the molar area.

Assessment of Inter-Condylar Distance as a guide for Arrangement of Maxillary Prosthetic Teeth

Background & Objectives: Inter-Condylar Distance (ICD) has been used as a reliable and fixed parameter for selection of mandibular anterior teeth and their arrangement. The objectives of this study were to determine the relationship of inter-condylar distance with maxillary inter-canine distance and maxillary inter-molar distance. Methods: This crosssectional study was conducted in the Department of Prosthodontics & Crown-Bridge, B.P. Koirala Institute of Health Sciences (BPKIHS) enrolling 120 dentate subjects those fulfilled the inclusion criteria. Maxillary casts were prepared and the distance between bilateral canine tips were measured using a Vernier caliper. The mesiobuccal cusp tips of maxillary first molars were marked and the distance was measured using the caliper. Inter-condylar distance was measured using arbritary face bow. The distance between the two condylar rods was measured in millimeters using Vernier caliper. Every distance was measured three times to assure the accuracy and mean taken. Data were recorded on the proforma for statistical analysis. Results: The ratio of intercondylar distance to the maxillary inter-canine distance was found to be 3.6:1 whereas that to intermolar distance was 2.6:1. Pearson correlation coefficients (r) for the ICD showed positive and significant correlation to both the inter-dental distances. (r - 0.33, (p

Determining of canine position by multiple facial landmarks to achieve natural esthetics in complete denture treatment

Statement of problemAnterior tooth selection is an important step in complete denture treatment as it plays a pivotal role not only in esthetics but also in mastication and pronunciation. However, conventional methods for tooth selection are not well established and rely on facial measurements and proportions, which vary among different ethnicities. PurposeThe purpose of this clinical study was to investigate the relationship between interalar width and intercanine distance and to compare different clinical methods for determining the position of the canine tooth. Material and methodsTwo hundred Thai participants (100 men and 100 women) aged 18 to 25 years with 6 full maxillary anterior teeth were enrolled in this study. The interalar width and intercanine distance were measured with digital vernier calipers and compared by using the paired-samples t test. To determine the canine position, 2 reference lines—the alar line (A line) and the inner canthus of the eye to alar line (IA line)—were drawn through the canine on both sides. The horizontal distances from each reference line to the canine cusp tip and distal contact point were evaluated and then analyzed using the 1-sample t test. ResultsAll measurements were significantly different between men and women (P<.01). Interalar width was greater than intercanine distance in both sexes. In men, the A line coincided with the canine distal contact point (P>.05). In contrast, the IA line was distal to the canine distal contact point by 3.5 ±3.6 mm on the left side and by 3.9 ±3.4 mm on the right side. In women, the A line was situated between the canine cusp tip and distal contact point. It was mesial to the distal contact point by 2.0 ±2.0 mm on the left side and by 1.8 ±2.0 mm on the right side. The IA line was distal to the canine distal contact point by 1.2 ±2.6 mm on the left side and by 1.6 ±2.7 mm on the right side. ConclusionsThe interalar width is greater than the intercanine distance in both sexes. The A line is more clinically relevant than the IA line for predicting canine position. The A line can directly determine the distal contact point of the canine in edentulous male patients. However, in women, a distance of approximately 2 mm should be added distal to the A line to locate the distal contact point of the canine on both sides.

Correlation Between Mesio-Distal Teeth Diameters and Arch Width

Objective: To verify the existence of a correlation between the mesio-distal size of teeth and the arch width by analyzing the data separately for maxillary and mandibular arch in patients with ideal occlusion . Material and Methods: 58 patients with ideal occlusion were studied, for a total of 276 files analyzed. Dental casts were then scanned using a professional scanner (Epson Perfection v 330) and images were obtained in TIFF format at 600 dpi. All single teeth measurements were carried out for all teeth of both arches using the VAM software (Vectra, Canfield Scientific, Fairfield, NJ, USA). The repeatability and reproducibility of the measurement method were evaluated using the Gauge R&R method. In case a correlation between tooth size and arch size is found to be significant, a linear regression analysis can be applied through the following statistical relationship: y=a+b*x, where y is the result (inter-molar distance “AvgB66” or inter-canine distance “Cusp 33”), and x the specific tooth. The a and b respectively represent the intercept (point of intersection between the line and the y axis) and the slope of the line that describes the regression ratio. Results: The statistical analysis highlights a significant correlation (p<1%) between the results of the mesio-distal measurements of each tooth and the two variables considered to define the size of each arch (“AvgB66” and “Cusp 33”). Based on these results, a numerical relationship y=a+b*x has been extrapolated. Thus, it is possible to calculate the estimated inter-molar or inter canine distance necessary to have the teeth aligned . Conclusion: The inter-canine and inter-molar distances can be estimated starting from measuring the mesio-distal diameter of a single tooth.

Morphogenic correlation between facial form and intercanine width - an aid in forensic dentistry

Background: Forensic odontology is a branch of forensic dentistry that utilizes dental remains for personal identification. When facial recognition is not possible, the facial form of the person can be reconstructed with the help of teeth present and dental structures available. The teeth in the maxillary intercanine region play a vital role for the same. The intercanine width varies considerably between different populations and races and its relation with other facial parameters can be used in personal identification and even facial reconstruction. Aim: The aim of the present study is to assess the correlation between the tooth form and face form by correlating the intercanine width with other facial parameters such as interpupillary distance, interalar distance, interzygomatic distance, and intercanthus distance in the Ethnic Tamil population. Materials and Methods: The study was conducted on a sample of 100 patients aged between 20 and 40 years. Five parameters, namely the intercanine width, interpupillary width, interalar distance, interzygomatic distance, and intercanthus distance was measured using a digital Vernier caliper. The data obtained were tabulated and analyzed using SPSS statistical analysis software. Unpaired t-test was used to compare the mean values of the parameters among males and females. Pearson's correlation was run to assess the relationship between the parameters and P &lt; 0.05 was considered to be statistically significant. Results: Among 100 participants, 50 were male and 50 were female. The mean intercanine width of males (35.1 mm ± 3.8) and females (33.1 mm ± 3.1), mean interzygomatic distance of males (110.8 mm ± 12.3) and females (106.7 mm ± 8.1), and mean interalar distance of males (26.2 mm ± 5.8) and females (28.3 mm ± 4.5) were found to be statistically significant. There was a significant, moderate correlation (r = −0.3; P &lt; 0.05) between the intercanine and intercanthus width in males but not in females. Conclusion: In the present study, a weak correlation existed between intercanine distance and other facial parameters. Several parameters determine the facial form and a combination of these parameters have to be considered thereby reconstruction of the face is possible for future prospectus in forensic dentistry.

A 3-D Finite Element Analysis of a Single Implant Retained Overdenture Reinforced with Short Versus Long Frameworks.

Due to its simplicity and patient satisfaction, an implant-retained overdenture has become the most preferred treatment for edentulous patients. Due to the presence of an attachment system at mandibular anterior region, however, base fracture is the most common complication of overdenture. This study aimed to evaluate the stress distribution and deformation on a symphyseal single implant retained mandibular overdenture using a three-dimensional finite element. Zirconia versus acrylic overdenture was investigated. Acrylic overdentures reinforced with short (over inter-canine distance) or long (extending between first molars) zirconia, cobalt-chromium alloy or polyetherketoneketone framework were also investigated. A load of 100 N was applied to the incisal edge of mandibular central incisors at a 30º angle. Results showed that zirconia overdenture had lower von Mises stress and deformation in its components than acrylic. Reinforcement of an acrylic overdenture with cobalt chromium or zirconia short frameworks reduced von Mises stress and deformation on its components. Reinforcement of an acrylic overdenture with polyetherketoneketone framework did not show any significant reduction in von Mises stress and deformation. Therefore, it can be concluded that using zirconia overdenture or reinforcing an acrylic overdenture with cobalt chromium or zirconia framework could increase the longevity of the prosthesis.

Correlation of Width of Anterior Maxillary Teeth with the Intercanine Distance, Distance from Inner to Outer Canthus of Right Eye and Width of First Three Fingers of Right Hand for Teeth Selection

Correlation of Width of Anterior Maxillary Teeth with the Intercanine Distance, Distance from Inner to Outer Canthus of Right Eye and Width of First Three Fingers of Right Hand for Teeth Selection

3D-analysis of unwanted tooth movements despite bonded orthodontic retainers: a pilot study

BackgroundRecently, reports of unwanted tooth movements despite intact orthodontic bonded retainers have increased. These movements are not subject to relapse but are classified as a new developed malocclusion. The aims of the present pilot study were to analyze the prevalence of unwanted tooth movements despite intact bonded cuspid-to-cuspid retainers and to identify possible predisposing factors.Materials and methodsPlaster casts of all patients finishing orthodontic treatment during three consecutive years were assessed before treatment (T0), after multibracket appliance debonding (T1) and after two years of retention (T2). After multibracket appliance treatment, all patients received a cuspid-to-cuspid flexible spiral wire retainer bonded to each tooth of the retained segment in the upper and lower jaw. The study group (SG) consisted of 44 patients (16 male, 28 female) with tooth movements (T1–T2) of the retained segment despite intact bonded cuspid-to-cuspid retainer and the control group (CG) of 43 patients (19 male, 24 female) without unwanted tooth movements. The casts of the SG were digitized, superimposed and measured. Using the Chi-square test, Fisher´s exact test and Mann–Whitney-U-test (p < 0.05), mandibular plane angle, incisor proclination, oral dysfunctions or habits (T0) and intercanine distance, overjet and interincisal relationship (T0, T1, T2) were compared between SG and CG.ResultsThe prevalence of patients with unwanted tooth movements in one or both jaws was 27.0%. Maxillary retainers were affected more often (20.9%) than mandibular retainers (14.1%). The median amount of tooth movements was 0 to 0.66 mm with large interindividual variations. Oral dysfunctions or habits at T0, such as a lack of interincisal contact at all time points, were associated with unwanted tooth movements.ConclusionUnwanted tooth movements occurred more often with maxillary than mandibular retainers. Patients with oral dysfunctions/habits and without interincisal contact had a higher prevalence of unwanted tooth movements.

CBCT and CAD-CAM technology to design a minimally invasive maxillary expander

BackgroundA large number of articles in recent years studying the effects of non-surgically assisted tooth- versus bone-borne maxillary expanders in growing patients have found no significant differences in mid-palatal suture disjunction or even dentoalveolar changes. This suggests the need for new criteria and better use of current technology to make more effective devices and enhance the benefits of conventional treatments. This article describes a titanium grade V computer-aided design/computer-aided manufacturing (CAD/CAM) maxillary expander supported by two miniscrews, along with a 3D printed surgical guide.MethodsThe first step was to obtain a digitized model of the patient’s upper maxilla. To simplify the process and ensure the placement of the device in a high-quality bone area, the patients’ digital dental cast was superimposed with a cone beam computed tomography (CBCT) scan. Improved resistance to expansion forces was secured through the use of 2 mm-wide miniscrews, long enough for bicortical anchorage. Placement site and direction were assessed individually in order to achieve primary stability. We chose a site between the second premolars and first molars, while the inclination followed the natural contour of the palate vault. A 3D-printed, polyamide surgical guide was designed to ensure the correct placement of the device with a manual straight driver.ResultsFavorable clinical results were presented with 3D images. We confirmed a mid-palatal suture parallel separation of 3.63 mm, along with a higher palatal volume, as well as increased intercanine and intermolar distance. Segmentation of the facial soft tissue showed an expansion of nasal airways and changes in nasal morphology.ConclusionsDigital models, CBCT and CAD/CAM technology, are essential to accomplish the goals proposed in this article. Further studies are necessary to establish safer miniscrew placement sites and insertion angles so as to achieve greater in-treatment stability. Both the clinician and the patient can benefit from the use of current technology, creating new devices and updating traditional orthodontic procedures.

USE OF BITEMARKS FOR HUMAN IDENTIFICATION BY USING INTER-CANINE DISTANCE AND MESIO-DISTAL WIDTH OF MAXILLARY INCISORS.

Aim: to determine the use of bite marks for human identification by using inter- canine distance and mesio-distal width of maxillary incisors. Introduction: Odontogenic evidence is considered to be the third most precise method of identification of human in forensic sciences. Bite-marks on the body are intentionally made, those found on food particles are usually impractically left by the offender at the scene of crime, these marks are of great importance in identification of the offender. The present study was aimed to determine the use of bitemarks for human identification by using inter-canine distance and mesio-distal width of the maxillary incisors. Materials and Methods: 40 consenting volunteers were included in the study. With the help of autoclaved Vernier calliper, the inter-canine distance and mesio-distal width of maxillary incisors were measured and bite on chocolate (CADBURY 5Star) was taken. Using Vernier calliper, Inter-canine distance and Mesio-distal width (2 maxillary central and 2 lateral incisors), were measured from the bite mark. Both measurements obtained were coded and matching was done by two doubly blinded examiners. Results: The probability of correct identification on the basis of IC distance and MD width obtained from bite-marks is 68.35%. The average proportion of correct matching is 0.78 for IC distance measurement and 0.46 for MD width. Conclusion: Metric method can be used for human identification by using bite-mark. IC distance is more reliable and efficient in human identification than MD width.

Changes of arch form at the end of orthodontic treatment, based on the Ricketts pentamorphic arch forms

Maintenance of the intercanine and intermolar distances reduces the risk of relapse and increases the chance of stability; these values represent the limits of the arch, resulting from the muscular balance of each patient. The ideal would be to reproduce the patient's arch form individually. The Ricketts pentamorphic arch forms allow the clinician to choose among 5 shapes, the one that best fits the patient's arch form. The objective of this study was to evaluate the effect of orthodontic treatment without extraction according to the pentamorphic arch forms on mandibular arches of different forms. Fifty patients were included in the study. For each patient, the pretreatment and end-of-treatment models were scanned by 3Shape Trios (3Shape, Copenhagen, Denmark) and transferred to the OrthoAnalyzer software (3Shape) version 2017-11.7.1.3 for measurements and superimpositions. The following measurements were made on the mandibular arches for both initial and final digitalmodels: arch depth; intercanine distance, the distance between the first premolars, the distance between the second premolars, the distance between the first molars, and the distance between the secondmolars. Three superimpositions were made: superimposition between the initial arch and the corresponding form of the pentamorphic arch forms, superimposition between the final arch and the corresponding form of the pentamorphic arch forms, and superimposition between the initial arch and the final arch. The largest difference between the superimposed arches in each region was measured. This study showed that intercanine distance (P=0.236), the distance between the first premolars (P=0.074), and the distance between the first molars (P=0.616) did not significantly change after orthodontic treatment. In contrast, the distance between the secondmolars (P=0.028) and the arch depth (P<0.001) increased significantly after orthodontic treatment. The mean of the largest difference in the absolute value of all the superimpositions is significantly different from the theoretical value 0 (P<0.001), but clinically, this difference is significant only in certain premolars and molars regions. This study has shown that the pentamorphic arch forms maintained the arch shape in the sagittal and transverse directions, except for an expansion of the distance between the mandibular secondmolars.

The relationship between the maxillary dental arch width, depth and circumference

This study was carried out on a random sample of (50) upper stone dental caste for intermediate school student (25 males and 25 females) aged (12-15) years from different areas of Mosul city. The correlation between the dental arch width, depth and circumference was calculated. It was found that male maxillary dental arch is greater in all dimensions than the female one. There was a weak correlation between the dental arch widths and the corresponding palatal vault depths. The correlation was moderate between the maxillary arch circumference and widths except at intercanine distance width, which it showed a high correlation and it was a weak between the arch circumference and the palatal vault depths.

Dental arch changes comparison between expander with differential opening and fan-type expander: a randomized controlled trial.

To compare posterior crossbite correction frequency and dentoalveolar changes of the expander with differential opening (EDO) and the fan-type expander (FE). Two-arm parallel randomized controlled trial. Forty-eight patients from 7 to 11 years of age were allocated into two groups. Twenty-four patients were treated with the EDO and 24 patients were treated with the FE. Block randomization was performed. The study was single blind. Digital dental models were acquired before treatment and 6 months after rapid maxillary expansion. The primary outcomes were crossbite correction rate and maxillary arch width changes. Secondary outcomes were interincisal diastema, arch perimeter, length, size and shape, and mandibular dental arch changes. The final sample comprised 24 patients (13 female and 11 male; mean initial age of 7.62 years) in the EDO group and 24 patients (14 female and 10 male; mean initial age of 7.83 years) in the FE group. The crossbites were corrected in 100 per cent of subjects from EDO group and in 75 per cent of patients in FE group. EDO showed greater increases in maxillary intermolar region (P < 0.001), while the FE demonstrated greater increases in the intercanine distance (P = 0.008). Increase in mandibular inter-first permanent molar distance was slightly greater in the EDO group (mean difference of 0.8 mm). Changes in arch length and perimeter were similar in both groups. Both expanders changed the maxillary arch shape. The post-treatment arch shape was larger in the anterior region for FE and in the posterior region in the EDO group. Discomfort during activation was reported by 54 per cent of the participants. A temporary change in the nasal bridge was reported by one patient from FE group. Maxillary arch width and shape changes were distinct between the EDO and the FE. Greater transversal increases of the anterior and posterior regions were observed for the FE and the EDO, respectively. A slightly greater mandibular spontaneous expansion was observed for the EDO only at the molar region. NCT03705871.