Narrow Arch Research Articles

How does arch form and interproximal contact size affect the 3D displacements and rotations of teeth: a finite element analysis.

The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF). Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar. Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models. Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.

Aortic Arch Phenotypes in Double Outlet Right Ventricle (DORV)-Implications for Surgery and Multi-Modal Imaging.

Abnormal aortic arches (AAAs) cover a spectrum of malformations, including abnormal laterality, branching patterns, and flow-limiting narrowing, which themselves vary from tubular hypoplasia, through discrete coarctation, to complete interruption of the arch. Neonatal surgery within the first days of life is necessary for most of these morphologies. Patch aortoplasty is widely used as it can offer a good haemodynamic result, being tailored to each combination of presenting pathologies. Our study hypothesis was that arch malformations are frequent in DORV and exhibit a plethora of phenotypes. We reviewed 54 post-mortem heart specimens from the UCL Cardiac Archive, analysing morphological features that would potentially influence the surgical repair, and taking relevant measurements of surgical importance. AAAs were found in half of the specimens, including 22.2% with aortic arch narrowing. In total, 70% and 30% of narrow arches had a subpulmonary and subaortic interventricular defect, respectively. Z-scores were significantly negative for all cases with tubular hypoplasia. We concluded that arch malformations are a common finding among hearts with DORV. Surgery on the neonatal aortic arch in DORV, performed in conjunction with other interventions that aim to balance pulmonary to systemic flow (Qp/Qs), should be anticipated and form an important part of multi-modal imaging.

A Guide to Orthodontic Devices for Trainees in Orthognathic Surgery

Purpose: Despite the interplay between orthodontics and orthognathic surgery, trainees in plastic surgery and oral and maxillofacial surgery do not receive formal training in orthodontics and associated hardware. This study aims to help surgical trainees better understand the role of orthodontic treatment in achieving enhanced dental occlusion and alignment and optimize surgical decision making. Methods: A review of recent literature was conducted to consolidate current practices for the use of orthodontic devices commonly used in orthognathic surgical patients. Results: Orthodontic treatments may be preventive, interceptive, and/or corrective. Braces and clear aligners are popular devices used to correct tooth positioning via 3 orders of control: first (“in-out” and rotation), second (mesio-distal angulation or “tip”), and third order (inclination or torque). Further, various treatments exist for skeletal and dental malocclusions, which may occur in transverse (crossbites, narrow arches) and/or sagittal (over/underbites) planes. Palatal expanders such as the Hyrax or Haas assist in correction of transverse deficiencies. Appliances for sagittal corrections typically take advantage of patient’s remaining growth and include a variety of headgear types (cervical, high-pull, occipital, reverse-pull), functional appliances (fixed or removable), or simply the use of interdental elastics. Conclusion: As patients are increasingly seeking orthodontic care in conjunction with surgery, it is important for surgical trainees to develop a strong understanding of the various orthodontic devices used.

Comparison of Malocclusion Prevalence, Type and Severity between Cerebral Palsy and Healthy Subjects: A Prospective Case-Control Study

Background: To analyze the prevalence, type and severity of malocclusions in a group of patients with cerebral palsy (CP) using a facial and occlusal analysis and the Dental Aesthetic Index (DAI). Methods: A prospective, case–control study was made of two groups, a cerebral palsy and a control group, with the determination of the facial and occlusion analysis in the three spatial planes. The Dental Aesthetic Index (DAI) was used to assess the severity of malocclusion. Results: The patients with CP presented a higher prevalence of increased facial lower third height and a greater tendency towards right-side canine and molar class II malocclusion, narrower transverse relationship and crossbite. The DAI scores were statistically significantly higher in the CP group. Increased physical impairment in the CP group was associated to greater DAI scores. Conclusions: The prevalence and severity of malocclusion were significantly greater in the CP group. The type of malocclusion predominantly found in these patients was molar class II, with open bite, increased overjet and a narrow arch. The CP group also presented mixed breathing with higher DAI scores and decreased facial lower third height.

PERBANDINGAN UKURAN GIGI DAN DIMENSI LENGKUNG ANTARA GIGI TANPA BERJEJAL DENGAN GIGI BERJEJAL

Tooth size and arch dimensions are hereditary factors that play a role in the occurrence of crowding teeth. The purpose of this study was to determine the difference in tooth size and arch dimensions between crowding and crowding teeth. This type of research is an observational study with a cross sectional approach. The sample of this study consisted of two groups. The sample of this study was a dental study model, which consisted of 36 pairs in each group. The results showed the total mesio-distal width of the maxillary anterior teeth (45.95 mm and 48.26 mm), the mandibular anterior teeth (35.92 mm), and 38.16), the maxillary teeth (95.82 mm and 99.47 mm), the mandibular teeth (87.60 mm and 91.50 mm), the inter-canine width maxillary buccal region (37.03 mm and 34.85 mm), maxillary inter-canine width palatal region (26.53 mm and 25.69 mm), buccal area of ​​mandibular inter-canine width (28.38 mm and 27.75 mm), the mandibular inter-canine width in the lingual area (20.38 mm and 19.90 mm), the maxillary inter-molar width in the buccal area (62.73 mm and 60.60 mm), the maxillary inter-molar width in the palatal area (37.86 mm and 35.10 mm), mandibular inter-molar width buccal area (56.51 mm and 55.31 mm), mandibular inter-molar width lingual area (34.10 mm and 31.66 mm), arch length maxillary arch (37.57 mm and 37.76 mm), mandibular arch length (32.63 mm and 32.77 mm), maxillary arch perimeter (96.95 mm and 94.68 mm), and mandibular arch perimeter (87.86 mm and 85.83 mm), Bolton's anterior ratio (78.19% and 79.13%), and Bolton's overall ratio (91.43% and 92.03%). The conclusion of the study showed that the crowding group had larger tooth size, narrower arch width, narrower arch perimeter, longer arch length, and larger anterior ratio and Bolton overall ratio compared to the crowding group.

Space maintainer ‘Y model’ as a preventive orthodontic treatment for paediatric patients: a case report

Background: Caries is one of the most common oral diseases that occur among children. Caries and dental trauma in children may cause early tooth loss, also known as premature loss, and result in occlusion abnormalities caused by the dental arch narrowing. A space maintainer is a preventive orthodontic appliance designed to maintain a narrow arch to prevent premature loss. Purpose: This study aims to describe the treatment of a case of space management in a patient with premature loss by using the space maintainer ‘Y model’. Case: An eight-year-old boy was accompanied by his mother, complaining that the lower posterior right tooth had been extracted. The mother was worried that the new tooth would have an overlapping growth. Case Management: The diagnosis was mandibular primary molar loss. The study cast was analysed based on Moyers 2.62 cm, Huckaba 2.24 mm, and curve determination 2.40 mm. The mandibular removable space maintainer treatment was performed on the patient and was followed by nine control visits every week. The outcome was a successful treatment from the use of the space maintainer ‘Y model’. Conclusion: The space maintainer treatment with the Y model in the paediatric patient showed a good result, evidenced by the tube opening of 1.2 mm, showing that the appliance followed lateral jaw growth.

Is the corticotomy assisted orthodontic treatment efficient in the expansion of narrow arches in adult patients?

Corticotomy assisted orthodontic treatment (CAOT) is a technique which, performing surgical cuts on the cortical alveolar bone around the teeth, induces a faster rate of orthodontic tooth movement. The development CAOT offers solutions to overcome many of limitations in adult orthodontic treatment, such as risk of hyalinization, root resorption, periodontal problems, lack of bone growth and a long therapy time due to slower tooth movement compared to adolescents. The purpose of this systematic review was to identify if CAOT is also useful for expanding narrow arches in adult orthodontic patients. An electronic research on PubMed until June 2020 was made with the combined search terms "corticotomy expansion," "corticotomy orthodontic expansion" and "corticotomy orthodontic." Six studies were included in this systematic review. The authors found discordant results in literature; however, it seems that CAOT can have better results than conventional expansion, but it cannot be considered as an alternative therapy for severe posterior cross-bite. CAOT have a greater predictability if done with bone grafting. The evidence of corticotomy as a help to palatal expansion in adult orthodontic treatment has not been well described in literature and only few published reports are available. Further testing in human beings are still necessary to confirm the validity of this technique.

Differences in Dental Arch Dimensions in a Sample of Kurdish Population among Different Occlusal Categories

It is essential to know dental arch dimensions to provide accurate diagnosis and treatment planning to ensure the satisfactory outcome of orthodontic treatment. The aim of the present study was to measure and compare dental arch dimensions of a Kurdish sample in Erbil city with normal and different classes of malocclusion. Arch width and length were measured by an electronic digital caliper on a total of 150 orthodontic models of school students aged 16–20 years of different occlusal relationships (Class I normal occlusion, Class I, Class II division I, Class II Division II, and Class III malocclusions). The results showed that (1) girls have smaller arch parameters than boys; (2) Class II division II malocclusion showed a significantly smaller upper inter canine width, arch length, incisor molar distance, and incisor canine distance when compared to all other groups; (3) the upper inter premolar and inter molar width were significantly narrower in Class II division I malocclusion than of normal occlusions and Class III malocclusion and also narrower in Class I malocclusion than in normal occlusions for both arches; (4) the arch length was significantly longer in Class II division I when compared to Class II division II, Class I malocclusions (P < 0.01), Class III malocclusion and Class I normal occlusion (P < 0.05), and (5) no statistically significant differences were found in all the arch dimensions for Class III malocclusion when compared with the normal occlusion. In conclusion, girls had smaller arch dimension than boys and Class II Division II malocclusion showed smaller arch in all dimensions while Class II division I malocclusion revealed narrower arch width and longer arch length.

Bimaxillary transverse constriction in adults: Short-term follow-up of non-surgical arch expansion.

Concurrent maxillary and mandibular expansion is a treatment option for patients with maxillary and mandibular transverse constriction. These patients do not present with crossbite but require expansion due to narrow arches and associated crowding, dark buccal corridors and decreased anterior arch contour. The objective of the study is to first establish Bimaxillary Transverse Constriction as an under-recognized malocclusion and second to evaluate whether in adults the maxillary and mandibular arches can be successfully and safely expanded. Pre- and post-treatment study models and lateral cephalograms of 31 adults with Bimaxillary Transverse Constriction expanded non-surgically were analysed. Thirty adult orthodontic patients who did not require expansion served as a control. Expanders were turned no more frequently than every other day in the maxilla and every third day in the mandible. Measurements in both arches made on OrthoCAD models were transarch widths, molar and premolar axial angulation, clinical crown height of posterior teeth and cuspids, and mandibular divergence. Retrospective comparison of the 2 groups used independent Student's t tests for mean differences between groups. At pre-treatment, the expansion group demonstrated significant transverse constriction compared with the control. Increased widths were achieved in the expansion group (4mm in the maxilla and 2.5mm in the mandible), while the control group was unchanged. The mandibular plane was unchanged. There was no buccal attachment loss. Non-surgical expansion in the maxilla and mandible is a viable treatment option for adult patients with Bimaxillary Transverse Constriction.

OP13.08: Failure of vacuum delivery is associated with a narrow subpubic arch angle

OP13.08: Failure of vacuum delivery is associated with a narrow subpubic arch angle

Influence of Oral Morphology on Speech Production in Subjects Wearing Maxillary Removable Partial Dentures with Major Connectors

Background/Aims: Speech impairment during the initial phase of removable partial denture (RPD) treatment can prevent patient adaptation to RPDs. This study was undertaken to investigate the influence of oral morphology on speech production in subjects wearing RPDs with major connectors. Methods: Two types of connectors were fabricated for 17 subjects with normal dentitions: covering the middle palate (M-bar) and the anterior/posterior palate (AP-bar). Four target sounds ([∫i], [t∫i], [çi], and [ki]) were evaluated under 3 recording conditions: no connector, M-bar, and AP-bar. The mean appearance ratios of correct labels (MARCs) were calculated as parameters representing speech production accuracy with the speech evaluation system. Subgroup analysis was conducted based on palate height, dental arch width, and front space volume of the oral cavity. Results: Based on the multiple linear regression test, a significant association was found between the MARCs of [∫i] with M-bar and front space (p = 0.036). In the subgroup analysis, the AP-bar had a significant effect on the MARCs of [∫i] among subjects with high palate (p = 0.026), narrow arch (p = 0.004), and small front space (p = 0.014). Conclusion: RPDs with major connectors could disturb speech production among patients with high palates, narrow arches, and small front spaces.

Features of facioscapulohumeral muscular dystrophy in oral and maxillofacial region and MRI analysis of facial muscles

Objective: To investigate the manifestation of facioscapulohumeral muscular dystrophy (FSHD) in oral and maxillofacial region. Methods: A total of 12 patients diagnosed as FSHD and 20 healthy volunteers were included in the study. Their medical history was collected from these patients. The decayed missing filled teeth (DMFT), calculus index-simplified (CI-S), occlusal relationship, maximal opening of mouth and maximum bite force were recorded. The impressions were taken to measure the maximal hight of palate and the width of palate. The lateral cephalometric radiographs were also taken to measure the mandibular plane-frankfurt horizontal plane angle (MP-FH). They finally received oral and maxillofacial region MRI examination to observe the masseter muscle, medial pterygoid muscle and lateral pterygoid muscle. The data were analyzed by t-test or Wilcoxon signed ranks test. Results: There was no significant gender difference in FSHD group. The average age of treatment was (27.5 ± 8.1) years and the average age of onset was (15.7±7.5) years. Nine patients liked to eat soft foods, 4 patients had difficulties of closing eyes, 8 patients had difficulties of cheek-bulging, 10 patients showed pouty lips and 9 patients had mesio-malocclusion. DMFT (4.0±2.3), CI-S (5.8±2.1), male maximal hight of palate (20.5±2.1) mm , female maximal hight of palate (17.9±1.6) mm, MP-FH (31.8°±2.2°) of FSHD group were greater than those of the control group. Male width of palate (34.8±1.4) mm, female width of palate (33.7±1.5) mm, male maximum bite force (451.7 ± 39.0) N, female maximum bite force (326.7 ± 21.6) N, maximal opening of mouth (3.5 ± 0.4) cm of FSHD group were less than those of the control group (P <0.05). Maxillofacial MRI showed muscle asymmetr in 11 cases of masseter and 6 cases of medial pterygoid muscle, 5 cases of lateral pterygoid, and these muscle showed mild fatty infiltration mainly concentrating in the grade 0, grade 1 and grade 2. Conclusions: The FSHD patients have poor oral hygiene, low masticatory function, limited mouth opening, high palate and narrow arch and different degree of malocclusion. The patients' masseter muscle, medial pterygoid muscles and lateral pterygoid muscles exhibit asymmetrical atrophy and fatty infiltration.

Dental arch dimensional changes after adenoidectomy or tonsillectomy in children with airway obstruction: A meta-analysis and systematic review under PRISMA guidelines.

Children with severe airway obstruction tend to have a vertical direction of growth, class II malocclusion, and narrow arches. Adenoidectomy and tonsillectomy were recommended for the promotion of balanced dentition growth in these children.The aim of this study was to determine the effect of adenoidectomy and tonsillectomy on the growth of dental morphology in children with airway obstruction. A comprehensive search of the Medline, Embase, Web of science, and OVID databases for studies published through to January 17, 2016 was conducted. Prospective, comparative, clinical studies assessing the efficacy of adenoidectomy, or tonsillectomy in children with airway obstruction were included. The weighted mean difference (WMD) and 95% confidence interval (CI) were used for continuous variables. Forest plots were drawn to demonstrate effects in the meta-analyses. Eight papers were included in our study. We found that adenoidectomy and tonsillectomy led to a significant change in nasal-breathing in children with airway obstruction. Children with airway obstruction had a significantly narrower posterior maxillary dental arch than children without airway obstruction (WMD = -0.94, 95% CI [-1.13, -0.76]; P < 0.001). After surgery, these children still had a significantly narrower dental arch than the nasal-breathing children (WMD = -0.60, 95% CI [-0.79, -0.42]; P < 0.001). In terms of dental arch width, malocclusion, palatal height, overjet, overbite, dental arch perimeter, and arch length, a tendency toward normalization was evident following adenoidectomy or tonsillectomy, with no significant differences evident between the surgical group and the normal group. The small number of studies and lack of randomized controlled trials were the main limitations of this meta-analysis. Following adenoidectomy and tonsillectomy, the malocclusion and narrow arch width of children with airway obstruction could not be completely reversed. Therefore, other treatments such as functional training or orthodontic maxillary widening should be considered after removing the obstruction in the airway.

OC04.03: Is a narrow subpubic arch angle associated with an increased risk of pelvic floor damage?

OC04.03: Is a narrow subpubic arch angle associated with an increased risk of pelvic floor damage?

Dental arches dimensions, forms and its association to facial types in a sample of Iraqi adults with skeletal and dental class II-division 1 and class III malocclusion(A cross sectional study)

Background: The association between facial types and dental arches forms has considerable implications in orthodontic diagnosis and treatment planning. The aim was to establish the maxillary and mandibular dental arches width and length in skeletal and dental class II division 1 and class III malocclusion groups, find out the most frequent dental arch form and facial type and the association between them and to check the gender differences. Materials and Methods: Frontal and lateral facial photographs and maxillary and mandibular occlussal photographs for 90 iraqi subjects with age 18-25 years old (45 males and 45 females) divided equally into three groups, the 1st group with class II division 1malocclusion (overjet more than 3mm but less than or equal to 6mm), the 2nd group with class II division 1malocclusion (overjet more than 6mm) while the 3rd group with class III malocclusion (edge to edge or reverse overjet).Six linear measurements for each maxillary and mandibular dental cast photographs and two liner measurements for frontal and profile facial photographs was analyzed with (AUTO CAD 2013), which simplified the analyzing process and reduced the time and effort spent on taking measurements directly from the records to facilitate work and to gain more accurate results. Results: All the mean value of dental arches and facial measurements were higher in male than female, the most frequent maxillary and mandibular dental arch form in the three groups was the mid arch form follow by the narrow then the wide arch form except in the mandibular dental arch of the 3rd group it follow by the wide then the narrow arch form.The most frequent facial type in the 1st group is the Mesoprosopic one,followed by the Leptoprosopic then the Euryprosopic face type while in the 2nd and 3rd group the most frequent facial type is the Leptoprosopic, follow by the Mesoprosopic then the Euryprosopic facial type. An association was found between mid arch form and the Mesoprosopic face type in the 1st group, while no clear association was found between dental arch form and facial type in the 2nd and 3rd group for both genders. Conclusions: It was concluded that there was an association between facial type and dental arch form in subject with class II division 1malocclusion (overjet not more than 6mm), while in subject with class II division 1malocclusion (overjet more than 6mm) or with class III malocclusion (edge to edge or reverse overjet) no clear association was found between dental arch form and facial type.

뇌성마비환자에서 가철성장치를 이용한 상악 전치부 돌출 완화 : 증례보고

14세 남환이 정기검진을 위해 내원하여 임상 구강검사 결과 상악 전치의 돌출과 상악궁 협착이 관찰되었다. 환아는 뇌성마비를 가지고 있었으나 간단한 설명을 이해하고 쉬운 지시를 수행할 수 있었으므로 가철성 장치를 이용한 교정치료를 시도하였다. 단계적이고 주의 깊은 접근을 통해 상악궁 협착 해소 및 상악 전치의 돌출을 완화할 수 있었다. 뇌성마비 환아의 경우 특징적으로 상악 전치의 돌출이 흔히 나타나는데, 이는외상의 위험에 쉽게 노출된다. 하지만 뇌성마비 환아에서 나타나는 특징적인 반사, 침 흘리기 습관, 행동조절의 어려움 등을 이유로 많은 임상의들이 교정 치료를 포기하게 된다. 적절한 환자 선정과 수행 가능한 치료목표를 세운다면, 뇌성마비 환아에서도 단계적이고 반복적인 행동조절과 약물을 이용하여 치료가 가능하다. 교정 치료를 통해 얻어진 상악 전치의 돌출 완화는 외상의 위험성을 줄이고 더 나은 심미성을 제공하는 긍정적인 효과를 가져오게 된다. 따라서 임상의들은 뇌성마비 환아의 치료에 대한 인식 변화 및 개선을 위한 적극적인 노력이 필요할 것이며, 뇌성마비 환아들은 더 나은 구강 건강을 영위할 수 있을 것이다. Cerebral palsy is one of the primary handicapping conditions of childhood. The prevalence of malocclusions in patients with cerebral palsy is approximately twice than in general population. Even though these high rates of malocclusions, most clinicians may feel uncomfortable about treating such problems to reduce inclination of anterior teeth because to reduce of protrusion makes to decrease risk of trauma. This is the case report about mitigation of maxillary anterior teeth protrusion in patient with cerebral palsy. A 14 year old boy who had cerebral palsy visited our dental hospital. He had severe protrusive maxillary anterior teeth and narrow arch form. He was experienced at using Castillo morales appliance in early childhood. He had mild mental retardation and was able to learn simple skills. He and his parents had willing to improve his dental problems. A gentle impression taking on maxilla was done. Removable appliance was made including median screw and labial bow. We provide a period of adaption for 3 weeks. After of anterior teeth through activation of labial bow was done once a month by dentist. The treatment carried out for 10 months and we could observe reduced labial inclination of maxillary right central incisor and more wide arch form. Hawley type retainer was set at maxilla for retention. In conclusion, accompanying careful case selection and treatment, patient with cerebral palsy can be treated and should not be ignored their orthodontic needs.

Establishment of Yemeni Dental Arch Form

Objective: To assess the dental arch forms of Yemeni adult sample.&#x0D; Materials &amp; Method: The Eucledian clustering method of analysis was utilized for the determination of dental arch form. A total of 398 study models were constructed and evaluated to do measurements for both arches using a modified sliding caliper gauge. Six dental cast measurements divided into three sagittal and three transverse measurements were utilized to represent the dental arch width and length measurements.&#x0D; Result: Narrow form is the most prevalent arch form (30.9%) followed by wide form (23.9%), their prominence appear more in females and the least prevalent arch form was the mid form (9.3%), while flat and pointed forms were in between 18.3% and 17.6% respectively.&#x0D; Conclusion: Five arch forms: narrow, wide, mid, pointed and flat were distinguished as unique forms for the dental arches, with the predominance of the narrow arch form were found among Yemeni adults.&#x0D;

COMPREHENSIVE ORTHODONTIC TREATMENT OF PALATALLY IMPACTED MAXILLARY CANINES

Comprehensive orthodontic treatment among adult patients that required multidisciplinary approaches has been increased since a lot of them could not avail themselves with any treatment decades ago. Treatment of impacted canine in adult orthodontic patient needs to be integrated into the overall orthodontic treatment scheme. The following case report described an orthodontic treatment of 33-year-old woman with convex profile, palatally impacted of left maxillary canines and single dental crossbite. Dental midline shift associated with narrow arch form of upper arch and asymmetric tooth amount. Management of this case was started by extraction of first upper premolars in the opposite site from impacted maxillary in order to overcome dental discrepancy problem. Surgical exposure allowed the potency natural eruption of the impacted tooth. After 24-months of treatment, the impacted maxillary canines took place as integral elements in dentition and Class I Canine relationship was achieved. The success of this comprehensive orthodontic treatment also considered biomechanical and periodontal condition during treatment based on proper evaluation and good prognostic of the impacted tooth position. Providing adequate space and surgical exposure during levelling aligning phase followed by orthodontic traction and gingivectomy, were the multidisciplinary approaches of this following case. In conclusion, biomechanical orthodontic treatment related to periodontal condition must be considered in comprehensive orthodontic treatment of adult patient.

Polynomial Analysis of Dental Arch Form of Nepalese Adult Subjects

Introduction: Human dental arch acquires stable form and dimensions with the attainment of adulthood. The orthodontic treatment regimen signifies the predetermination of the shape and type of dental arch form of a particular adult population to harmonize with their natural pattern. The use of predetermined arch form helps in diagnosis, treatment planning and stability of orthodontic treatment results. Objective: To analyze the dental arch forms of Nepalese adults and to classify them into morphological types. Materials &amp; Method: Predetermined transverse and sagittal dimensions on dental stone models of one hundred Nepalese adults aged 17-32 years with normal occlusion and dentofacial proportion were measured using standardized Boley gauze. The analysis was done according to Raberin’s mathematical sixth degree polynomial method. The study compared the gender difference among the Nepalese samples. Result: The distribution of the Nepalese arch form types were; 26% flat arch, 24% wide arch, 19% pointed arch, 18% narrow arch and 13% mid arch. Conclusion: Considerable variation in distribution of dental arch form types found between Nepalese male and female samples and among population groups. The analysis enables the mathematical method that predetermines the dental arch form of the individual orthodontic patient.DOI: http://dx.doi.org/10.3126/ojn.v3i1.9267 Orthodontic Journal of Nepal, Vol.3, No.1, 2013: 7-13

Glasgow Central station: a new bridge, track and platforms

Glasgow Central station is one of the busiest railway stations in the UK outside London, with approximately 38 million people using it each year and an average of 1100 trains per day. The original station was opened by the Caledonian Railway in July 1879 and comprises a labyrinth of masonry and brick arches linked by vaulted arches and supported on substantial masonry piers founded in alluvial deposits. In 2009, as part of their continued commitment to improve rail services in Scotland, Network Rail commissioned the construction of two new tracks into the station, the first for 100 years. This presented a significant engineering challenge as the proposed alignment for the new tracks squeezes through the existing narrow masonry arch entrance structure, runs above a line of vaulted arches, which house a nightclub, theatre and restaurant, and is carried over the existing short-stay car park and ramp on a new reinforced concrete bridge. The new structures had to be supported on the existing Victorian infrastructure, demanding innovative, practical design solutions and skilful construction techniques to enable them to be built quickly and safely in a confined, busy public place.