Arch Form Research Articles

Determination of Maxillary and Mandibular Arch Width in Angle’s Class I Patients

Introduction: The transverse dimension plays a key role in smile. Maintaining the pretreatment arch form is a key to obtaining stable results. Objectives: The main aim of this study was to determine mean intercanine arch width and mean intermolar arch width in Angle’s class I patients. Methods: Seventy-six pretreatment casts were obtained from the records of patients who sought orthodontic treatment in Orthodontics and Dentofacial Orthopedics. Four parameters were used in this study namely; intercanine arch width and intermolar arch width in maxilla and mandible. Linear measurements were carried out with digital caliper. Kappa test was done for intra-observer reliability. Shapiro-Wilk test was done to determine the normal distribution of data. The Pearson Correlation test was done to assess the correlation between intercanine and intermolar arch width in maxilla and mandible. The independent t-test was used to compare between intercanine and intermolar arch width with male and female. Results: Mean intercanine arch width in maxilla and mandible were 35.41±1.47 mm and 26.85±1.59 mm respectively. Mean intermolar arch width in maxilla and mandible were 53.82±2.82 mm and 51.71±2.60 mm respectively. Statistically significant difference was found between intercanine and intermolar arch width in maxilla and mandible between male and female. The intercanine and intermolar arch width in maxilla and mandible has significantly low correlation. Conclusions: Intercanine and intermolar arch width in male and female were statistically significant and male has lager intercanine and intermolar arch width than female.

A novel method for measuring the direction and angle of Central ray and predicting rotation center via panorama phantom.

The aim of this study is to propose and evaluate a novel method for measuring the central ray direction and detecting the rotation center of panoramic radiography using the panorama phantom. To determine the central ray direction, two points passing through the same x-coordinate in a panoramic radiograph were identified and connected. The angles formed by the central ray with the midline and the angle to the arch form were measured using mathematical calculations. Further, by analyzing the continuous changes in the central ray obtained in this manner, the movement of the rotation center was detected and visualized. The angle between the central ray and the midline exhibited a progressive decrease from the anterior to the posterior direction. With regards to the arch form, the angle of the central ray exhibited an increasing pattern as it moved from the anterior to the posterior direction, culminating in its peak value at the lower second premolar cusp region, followed by a consistent decrease. The rotation center approximately started from the distolateral aspect of the coronoid process and then anteromedially moved to the midline in a curved line passing between the mandibular notch and coronoid process. By using the panorama phantom, we successfully obtained the central ray direction and detected the rotation center of the panoramic radiography.

Effect of Inter-Implant Distance on Fracture Resistance of Implant-Supported Provisional Fixed Dental Prosthesis.

This study aimed to identify the ideal interimplant distance for optimum outcome on immediately loaded implant supported prosthesis. Hence this study was taken up to analyze the effect of varying interimplant distance on fracture resistance of implant supported provisional fixed dental prosthesis (FDP). A total of 24 bis-acrylate composite resin samples were prepared. Interimplant distance was present in the metal die for placement of dummy implants at distances of 14 mm, 21 mm, and 30 mm respectively. Wax-up for 3-unit, 4-unit, and 5-unit implant-supported provisional restoration was made. Silicone molds were used for making multiple interim prostheses using bis-acrylate composite material. All samples were subjected to fracture test in the universal testing machine with a crosshead speed of 1 mm/min. All samples were loaded with gradual force starting from 100 N until it fractured. The load was applied at the center of prosthesis. Data was analyzed by one-way analysis of variance and Bonferroni post hoc test. Mean fracture resistance of 3-unit provisional FDP at 14 mm of interimplant distance showed 1342.61 ± 179.15 N. Mean fracture resistance of 4-unit provisional FDP at 21 mm of interimplant distance showed 1420.44 ± 170.37 N. Mean fracture resistance of 5-unit provisional FDP at 30 mm of interimplant distance showed 791.61 ± 203.59 N. Both 14 mm and 21 mm of interimplant distance are suitable span lengths to be considered for the optimum outcome during immediately loading with implant-supported provisional restorations. Limitations of the study were that force application was static in nature and not dynamic and the arch form was not "U" shaped but longitudinal using Bis-Acryl material only with no cantilever. Future studies can be done to evaluate the fracture resistance of bis-acrylate material considering biomechanics and arch form of natural dentition. Distal cantilever should be considered along with different material for fabricating provisional restoration.

Morphometric Evaluation of the Maxillary Arch Using Cone Beam Computed Tomography

Objective: Anatomically, a dental arch is a result of natural teeth being positioned on the alveolar bone. The purpose of this study is to assess the morphological characteristics of various maxillary arch types using Cone Beam Computed Tomography (CBCT) and ascertain their prevalence. Methods: This retrospective study analyzed 200 randomly selected maxillary CBCT images from patients aged 18–65. Measurements were interpreted using various planes, and maxillary arch forms were classified according to the House dental arch classification in the axial region of the CBCT images. Results: Patients over 45 years old had significantly higher mean canine-palate and first molar-palate measurements compared to younger groups, particularly the 18–25 age group, which showed a higher hard palate–anterior mean than the 25–35 group. Class II cases had a significantly higher mean canine-palate than Class I and III cases. Class II cases also exhibited higher first molar-palate and canine-anterior means compared to Class I and III. In contrast, Class I cases had a higher canine-canine mean than the other classes. Conclusion: Morphologic measurements are crucial for guiding specialists in diagnosis and treatment, enhancing the ease and accuracy of clinical practice.

MRI susceptibility artefacts caused by orthodontic wire.

To evaluate magnetic susceptibility artefacts produced by orthodontic wires on MRI and the influence of wire properties and MRI image sequences on the magnitude of the artefact. Arch form orthodontic wires [four stainless steels (SS), one cobalt chromium (CC) alloy, 13 titanium (Ti) alloys] were embedded in a polyester phantom, and scanned using a 1.5-T superconducting magnet scanner with an eight-channel phased-array coil. All wires were scanned with T1-weighted spin echo (SE) and gradient echo (GRE) sequences according to the American Society for Testing and Materials (ASTM) F2119-07 standard. The phantom also scanned other eight sequences. Artefacts were measured using the ASTM F2119-07 definition and OsiriX software. Artefact volume was analysed according to metal composition, wire length, number of wires, wire thickness, and imaging sequence as factors. With SE/GRE, black/white artefacts volumes from all SS wires were significantly larger than those produced by CC and Ti wires (P < .01). With the GRE, the black artefacts volume was the highest with the SS wires. With the SE, the black artefacts volume was small, whereas white artefacts were noticeable. The cranio-caudal extent of the artefacts was significantly longer with SS wires (P < .01). Although a direct relationship of wire length, number of wires, and wire thickness with artefact volume was noted, these factors did not influence artefact extension in the cranio-caudal direction. Ferromagnetic/paramagnetic orthodontic wires create artefacts due to local alteration of magnetic field homogeneity. The SS-type wires produced the largest artefacts followed by CC and Ti.

Determining patterns of the vertical load on a covered wagon roof with a frame in the form of a triangular arch

The object of this paper is the processes of perception and redistribution of loads in the roof of a railroad covered wagon with a frame in the form of a triangular arch. To reduce the tare of the covered wagon, it is proposed to improve the structure of its roof. A feature of this improvement is that the roof frame is made in the form of a triangular arch with a reinforcing belt. This contributes to the reduction of the total mass of the roof compared to a typical structure. The selection of execution profiles of the beams forming the arch is carried out according to the maximum values of the moments that act in their cross-section. Taking into account the chosen profile of the arches, the calculation of the strength of the roof when it receives vertical loads was carried out. It was established that the strength of the roof under the considered load schemes is within the permissible stress values. Since the improvement of the roof structure contributes to the reduction of its weight by 1.8 % compared to the prototype, the movement of the covered wagon was evaluated under conditions of moving while empty. To this end, a mathematical modeling of the load of the covered wagon in the vertical plane during its movement along the joint unevenness was carried out. On the basis of the performed calculation, it was established that the movement of the wagon is assessed as "good". Special feature of the results is that the reduction of the tare of the supporting structure of the wagon was achieved by improving its roof, as the least loaded unit. The field of practical application of the results is railroad transport, including other areas of mechanical engineering. The conditions for the practical use of the results are a symmetrical roof load scheme in operation. The results of this research could contribute to advancements related to the design of modern structures of freight wagons with improved technical and economic indicators

Space management using Transpalatal arch in mixed dentition phase: A case report

Introduction: The early exfoliation of primary molars during the mixed dentition phase often results in disruptions to the normal development of occlusion. An alternative option for space management in the maxillary arch besides the commonly used Nance palatal holding appliance is the transpalatal arch which allows some amount of space regaining. Case report: A 9 year old female reported with a complaint of missing tooth in the upper right back tooth region since 2 years. On examination, there was premature loss of the right primary maxillary first molar causing space deficiency in the arch form. A treatment plan was made for space regaining and distalization with transpalatal arch custom made with 0.9mm stainless steel wires and soldered to the molar bands. The treatment spanned for 10 months with the eruption of the permanent successor in correct arch form. Conclusion: Although the use of transpalatal arch is limited in pediatric dentistry, it can be used for correcting minor space discrepancies of the maxillary arch. More number of cases need to be studied for extending the use of the appliance in interceptive orthodontics.

An in-vivo Analysis of the Positional Relationship of Palatal Rugae with Maxillary Teeth in Different Arch Forms Among Young Dentulous Gujarati Individuals-A Pilot Study

Background- The palatal rugae are transverse folds of tissue located in the anterior portion of the hard palate. They are considered to be reliable landmarks with manifold uses in the field of orthodontics and forensics. The current study was carried out with the aim of determining if a positional relationship of palatal rugae exists with the maxillary teeth in individuals with different maxillary arch forms. Material and method- The study was carried out in 100 participitants (87 females and 13 males) . Irreversible hydrocolloid impressions were made and casts were poured in Type 3 dental stone. The casts were divided according to arch forms as taper, ovoid and square. Palatal rugae on the casts were assessed digitally and the position of the most posterior rugae evaluated in relation with the adjacent maxillary teeth. Results –It was observed that the palatal rugae had a higly significant positional relationship with the maxillary posterior teeth(p value &lt;0.0001) . In the ovoid and square arches, majority of the individuals had the most posterior rugae lying at the level of distal margin of 2nd premolar while in cases of taper dental arches, maximum number of individuals had the distal margin of 1st premolar coincide with the most posteriorly located rugae. Conclusion- Hence, it can be concluded that the most posterior limit of the rugae may serve as a reliable guide for the arrangement of the maxillary teeth in different arch forms. Key Words- Palatal Rugae, maxillary anterior teeth , denture aesthetics

Comparative evaluation and co-relation in variation of curve of Spee and curve of Wilson in Class II div. 1, Class II div. 2, and Class III as against Class I malocclusion in central India population- an in vitro study

Introduction Getting acceptable cosmetic results in the soft tissues of the face serves as the foundation for orthodontic treatment planning. Also, in order to achieve healthy static and dynamic occlusal interactions, the teeth must be positioned within the basal bone at the correct position, angle, and inclination. To avoid periodontal issues, provide stability, and achieve a functional occlusion, it is essential to ascertain the individual’s dental arch form before starting of treatment and thus to utilise the mechanics that follow throughout the treatment. Objectives To evaluate and compare variation in Curve of Spee and Curve of Wilson in Class II Div.-1, Class II-Div-2 and Class-III as against Class I malocclusion in central India population. Methodology Irreversible hydrocolloid impression will be taken with perforated metal stock trays and stone cast will be poured. This will be scanned using CAD CAM machine and curve of Spee and Wilson will be measured using reverse engineering. Expected Result It will assist us in treatment planning for preventing periodontal issues, assuring stability, and achieving functional occlusion by evaluating and comparing the Spee and Wilson curves in Class II Divison-1, Class II Divison-2, and Class-III malocclusion with Class-I malocclusion. Conclusion Every single patient receiving orthodontic treatment has the COS, which is crucial to achieving a stable occlusion. Almost every patient who receives orthodontic treatment eventually experiences the Spee Curve. Since there aren’t many studies examining the relationship between the Curves of Spee and Wilson, their impact on dentoskeletal morphology, and their role in occlusal stability.

Model analysis through two-dimensional evaluation of alveolar changes of untreated unilateral cleft lip and palate infants

The primary objective of therapeutic interventions for unilateral cleft lip and palate (UCLP) is to reestablish typical role and anatomy. The efficacy of nasoalveolar molding relies on the age at which it is initiated, thus early initiation is recommended. Evaluating the success of presurgical orthopedics involves assessing the after-treatment maxillary arch form and proportions in UCLP infants and comparing them to age-matched infants without clefts. Untreated UCLP cases exhibit various changes in the transverse and angular dimensions of the alveolar segment. Utilizing digital analysis of UCLP plaster casts through Photoshop software (version 24.0.0) can serve as an alternative method to predict changes in cleft width, arch width, and angular measurements in untreated cases.

The association between dental and dentoalveolar arch forms of children with normal occlusion and malocclusion: a cross-sectional study

BackgroundSymmetrical and coordinated dental and alveolar arches are crucial for achieving proper occlusion. This study aimed to explore the association between dental and dentoalveolar arch forms in children with both normal occlusion and malocclusion.Methods209 normal occlusion subjects (5–13 years, mean 8.48 years) and 199 malocclusion subjects (5–12 years, mean 8.19 years) were included. The dentoalveolar arch form was characterized by the smoothest projected curve representing the layered contour of the buccal alveolar bone, referred to as the LiLo curve. Subsequently, a polynomial function was utilized to assess dental and dentoalveolar arch forms. To facilitate separate analyses of shape (depth/width ratio) and size (depth and width), the widths of dental and dentoalveolar arch forms were normalized. The normalized dental and dentoalveolar arch forms (shapes) were further classified into 6 groups, termed dental/dentoalveolar arch clusters, using the k-means algorithm.ResultsThe association between dental and dentoalveolar arch clusters was found to be one-to-many rather than one-to-one. The mismatch between dental and dentoalveolar arch forms is common in malocclusion, affecting 11.4% of the maxilla and 9.2% of the mandible, respectively.ConclusionsThere are large individual variations in the association between dental and dentoalveolar arch forms. Early orthodontic treatment may play an active role in coordinating the relationship between the dental and dentoalveolar arch forms.

Comparative evaluation and co-relation in variation of curve of Spee and curve of Wilson in Class II div. 1, Class II div. 2, and Class III as against Class I malocclusion in central India population- an in vitro study.

Getting acceptable cosmetic results in the soft tissues of the face serves as the foundation for orthodontic treatment planning. Also, in order to achieve healthy static and dynamic occlusal interactions, the teeth must be positioned within the basal bone at the correct position, angle, and inclination. To avoid periodontal issues, provide stability, and achieve a functional occlusion, it is essential to ascertain the individual's dental arch form before starting of treatment and thus to utilise the mechanics that follow throughout the treatment. To evaluate and compare variation in Curve of Spee and Curve of Wilson in Class II Div.-1, Class II-Div-2 and Class-III as against Class I malocclusion in central India population. Irreversible hydrocolloid impression will be taken with perforated metal stock trays and stone cast will be poured. This will be scanned using CAD CAM machine and curve of Spee and Wilson will be measured using reverse engineering. It will assist us in treatment planning for preventing periodontal issues, assuring stability, and achieving functional occlusion by evaluating and comparing the Spee and Wilson curves in Class II Divison-1, Class II Divison-2, and Class-III malocclusion with Class-I malocclusion. Every single patient receiving orthodontic treatment has the COS, which is crucial to achieving a stable occlusion. Almost every patient who receives orthodontic treatment eventually experiences the Spee Curve. Since there aren't many studies examining the relationship between the Curves of Spee and Wilson, their impact on dentoskeletal morphology, and their role in occlusal stability.

Study on soil pressure of loose soil in cohesive soil tunnel considering soil arch effect

Soil pressure in clay formation tunnels is closely related to soil arch effect and the development of slip surfaces. Firstly, numerical simulation software is used to simulate the actual situation of tunnel excavation, and the change rule of the slip-cracking surface of cohesive soil is analyzed. Secondly, based on the numerical simulation results and the ellipsoid theory, the pressure formula of Terzaghi loose Earth is modified considering that the principal stress trace is catenary. Finally, the calculation results are compared with the finite element calculation results to verify the rationality of the formula in this paper. The relationship between the internal friction angle, cohesion force c, eccentricity ε, looseness coefficient β, and the pressure of loose Earth is further studied. The results show that there is a gap between the sliding crack angles with or without dilatancy angle and it will affect the development form of soil arch. The slip angle decreases gradually with the increase of the buried depth ratio H/D and becomes stable when the buried depth ratio H/D≥3. Compared with deep-buried tunnels, the increase of internal friction angle in the shallow-buried tunnel is more conducive to reducing the overlying soil pressure. The loose soil pressure decreases with the increase of eccentricity ε and loose coefficient β, and the influence of eccentricity ε on loose soil pressure is significantly greater than that of loose coefficient β. Therefore, the change of eccentricity ε should be paid close attention in the project.

Experimental study on cement-based materials for grouting/replacement of broken rock mass in coal mine

In deep high-pressure mines, the surrounding rock of soft broken roadways often faces issues such as poor anchorability, support difficulties, high maintenance costs, and the inadequacy of traditional materials for site requirements. To tackle these challenges, this study focuses on grouting reinforcement in coal mine sites and prefabricated bearing arch form (grouting or replacement) under specific conditions, aiming to meet the material requirements. Through an orthogonal test, various properties of cement-based materials were investigated, including fluidity, initial setting time, water separation rate, early (≤1d) compressive strength, fracture strength, and later (28d as a reference) strength. The objective was to develop a cost-effective cement-based material with high strength and toughness, suitable for underground coal mines. The experimental results demonstrate that the self-developed cement-based materials exhibit rapid setting, excellent fluidity, high early strength, and strong durability compared to traditional alternatives. Analyses of the comprehensive properties reveal that the influencing factors, in order of significance, include the mass ratio of cement and sand, water cement ratio, rubber content, and bonding mortar master material content. By employing extreme treatment and efficiency coefficient methods, the comprehensive performance of materials under different ratios was evaluated. Consistent findings were obtained, indicating that the optimal mass ratio of cement-based materials is 500:500:20:15:10:5:8:10 for cement, sand, fly ash, silica fume, mineral powder, steel slag powder, bonding mortar master material, and rubber, respectively. Additionally, the best comprehensive performance was achieved with a water cement ratio of 0.5, which confirms the results of the orthogonal test. Macroscopic failure characteristics and SEM microscopic analysis further validate the superior performance of the materials under the aforementioned ratio. The reaction process of the material can be roughly divided into four stages: initial hydrolysis stage, induction stage, acceleration stage, decay and stability stage, and finally the formation of stone body. A comparison with ordinary materials highlights the advantages of the developed cement-based materials, and suggestions are proposed for the development of field-applicable materials.

‘Digastricus’ axillary arch: A potential source of hyperabduction syndrome- Case report

Axillary arch is an anatomical variant musculo-tendinous structure that originates from the latissimus dorsi muscle and often inserted to the pectoralis major muscle. Being musculo-tendinous, its one end is generally muscular and another end is tendinous. Here we report a variant muscular arch with its both ends muscular and were joined by an intermediate tendinous slip; thus, the name digastricus axillary arch. This variant form of axillary arch was encountered unilaterally in an elderly female cadaver and appeared to be compressing the neurovascular structures at the vicinity of axilla. Presence of axillary arch known to cause various complications such as brachial plexus compression, hyperabduction syndrome, thoracic outlet syndrome etc. The clinicians, therefore must have a prior knowledge of rare existence of axillary arch muscle before considering differential diagnosis in the patients presenting upper extremity neurovascular symptoms without demonstrable compressions&#x0D; Bangladesh Journal of Medical Science Vol. 23 No. 02 April’24 Page : 542-545

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

Obtaining more accurate complete arch implant digital scans with the aid of a geometric pattern: A dental technique

A technique to obtain more accurate complete arch implant digital scans and virtual casts is described. In order to obtain complete arch implant digital scans with greater accuracy, short-span intraoral digital scans are superimposed with the aid of a geometric pattern. Therefore, the technique takes advantage of the accuracy of intraoral scanners to obtain digital scans of reduced spans. Two virtual designs of the geometric pattern have been made available online: one for maxillary arches and one for mandibular arches. From these virtual designs, new virtual designs of geometric patterns of different sizes and shapes can be created to better fit different arch forms and implant positions.

The Influence of Sidedness in Unilateral Cleft Lip and Palate on Mid Facial Growth at Five Years of Age.

To determine whether facial growth at five years is different for children with a left versus right sided cleft lip and palate. Retrospective cohort study. Seven UK regional cleft centres. Patients born between 2000-2014 with a complete unilateral cleft lip and palate (UCLP). 5-Year-Old's Index scores. 378 children were included. 256 (68%) had a left sided UCLP and 122 (32%) had a right sided UCLP. 5-Year-Old's index scores ranged from 1 (good) to 5 (poor). There was a higher proportion of patients getting good scores (1 and 2) in left UCLP (43%) compared to right UCLP (37%) but there was weak evidence for a difference (Adjusted summary odds ratio 1.27, 95% CI 0.87 to 1.87; P = .22). Whilst maxillary growth may be different for left versus right sided UCLP, definitive analysis requires older growth indices and arch forms.

Mechanical characteristics and stability analysis of an innovative type of steel–concrete composite support in shallow-buried excavation tunnels

Under the influence of the principle of New Austrain Tunnelling Method (NATM), the initial support structure of shallow-buried tunnels in urban soft rock mainly adopts the forms of section steel arches or lattice girder arches combined with bolt-mesh-shotcrete. In order to solve the problems of tunnel deformation and collapse caused by untimely support or insufficient support strength during the construction process, the concept of “timely and high-strength support” was put forward, the high-strength steel pipe grid (HSPG) arch was innovatively designed, and the steel pipe grid bolt-shotcrete (SPGB) structure was established. Next, the flexural bearing performance and failure modes of the joint component and jointless component of the HSPG arch were analyzed, and the design scheme was also optimized by finite element simulation. Then, the full-scale model test of steel pipe grid concrete component (SPGC) under the pure bending load was conducted to explore the coupling bearing effect in a laboratory. In addition, relying on the underground excavation tunnel project of urban subway, the characteristic curves and stability coefficient of surrounding rock and SPGB structure were given by using the principle of convergence-confinement method. Theoretical calculations and on-sit measurements showed that SPGB structure had good adaptability in weak surrounding rock tunnel. In general, the research results were of great significance for clarifying the bearing mechanism and applicable conditions of SPGB structure, and also provided a reference for its further application in the tunnel and underground engineering.

Archform

The basic principle of arch form in orthodontic treatment is that within reason, the patient’s original arch form should be preserved. These variations in arch form however, are not reflected in the preformed arch wires presently available and it is important to keep in mind during orthodontic treatment that if they are used, their shape should be considered a starting point for the adjustments necessary for proper individualization. Today, however, many normal variations are emphasized more than the specific type of arch forms. Recent studies nullify the existence of a single ideal arch-form template, indicating that dental arch forms are highly individual, and defining a single generalized shape and using variations of it should be avoided..