Saddle Angle Research Articles

A study of cephalometric appraisal of the inheritance of craniofacial pattern in Gorkhas

The phenotypic expression of biologic variability expressed in the craniofacial complex is influenced by constant interplay of heredity and environmental factors. The aim of this study was to observe the pattern of inheritance of cranio-facial complex in Gorkhas. Gorkhas are the original inhabitants of NEPAL in the slopes of HIMALAYAS and they generally marry strictly in their race. 76 individuals from 19 Gorkha families (son, daughter and both parents); were selected. Eight angular (saddle angle, articular angle, gonial angle, N-S-Gn, N-S-Go, SNA, SNB and ANB angles) and four linear (anterior facial height, posterior facial height, overjet and overbite) variables were measured from lateral head cephalograms and the values of the variables were evaluated and compared. It was found that the Inheritance of cranio facial pattern has shown significant coefficient of correlation from mother to offsprings for jarabak ratio, father to son for NS-Gn and NS-Go angle, father to daughter for articular and ANB angles. Different parts of craniofacial complex represents the resultant of morphology and size variation. Each one of these components are in turn influenced by many genetic and environmental factors.

Cranial base and airway morphology in adult Malays with obstructive sleep apnoea

Abstract Background Obstructive sleep apnoea (OSA) has been described as a public health problem comparable to smoking in its impacts upon society. Objective To compare the differences in cranial base and airway morphology in Malay adults with and without OSA using finite element analysis (FEM). Method Lateral skull radiographs of 38 adult Malays aged 18–60 years were divided into two groups of 19 (13 male, 6 female). The first group consisted of 19 patients with OSA, defined as an apnoea-hypopnea index > 5/hr of sleep, diagnosed with overnight polysomnography. The second group consisted of 19 healthy, non-OSA control subjects. For each lateral skull radiograph 27 homologous landmarks, which encompassed the naso-oropharyngeal airway, were digitised using MorphoStudio software. The mean OSA and control 2D airway configurations were computed and subjected to t-tests and FEM. Results The mean 2D OSA airway was statistically different from the mean control airway (p < 0.01). Inter-landmark analysis revealed that the cranial base saddle angle was more acute in the OSA group (153.9 degrees ± 3.4) compared to the control group (158.3 degrees ± 2.5; p < 0.01). In addition, using pseudo-coloured FEM a relative 58 per cent decrease in nasopharyngeal airway area was found above and behind the soft palate. As well, a 32 per cent decrease in oropharyngeal airway area was located behind the base of the tongue, with a 23 per cent decrease in hypopharyngeal area near the level of the hyoid bone. In contrast, a 96 per cent increase in area associated with downward displacement of the hyoid bone was detected. Conclusion Functional airway impairments associated with OSA can be quantified and localised in Malay patients, and are predominantly associated with the morphology of the posterior regions of the cranial base.

A study on craniofacial morphology of Japanese subjects with normal occlusion and esthetic profile

This study was designed to properly characterize the cephalometric values of Japanese individuals with both normal occlusion and esthetic profiles. Multivariate statistics were applied to analyze the collected data. Cephalometric values identified are expected to help in the simplification of orthodontic diagnosis. Lateral cephalometric radiographs from 50 men and 50 women with normal occlusion were traced and the dimensions of hard and soft tissues recorded. The corresponding values were classified by cluster analysis, and selected representative values were subjected to principal component analysis. From these values, characteristics of hard and soft tissue morphology were extracted. The subjects were grouped by sex, and subdivided into esthetic and unesthetic profile groups. The principal component scores from each group were plotted on a scattergram and the characteristics of each group investigated. The hard tissue characteristics in men with esthetic profiles were primarily vertical factors, including a tendency for smaller lower facial heights, a smaller mandibular plane angle, and a larger Nasion-ANS/ANS-Menton (N-ANS/ANS-Me). Soft tissue features included a more posteriorly placed maxilla and a high nasal crest. These features yield a less marked maxillary prognathism and a greater nose prominence. In females, hard tissue characteristics associated with esthetic profiles primarily involved the cranial base and posterior facial area. These included a smaller saddle angle, larger articulare angle, and smaller Sella-Articulare/Articlare-Gonion (S-Ar/Ar-Go). Female soft tissue characteristics primarily included retracted upper and lower lips, a shallow inferior sulcus with a smaller lower lip-Frankfort plane angle, and a shorter mentolabial sulcus and subnasale perpendicular-upper lip.

Cephalometric features of skeletal Class I, II and III (A comparative study)

Aims: To identify the cephalometric features of three skeletal jaw relations (Class I, II and III). Materials and methods: one hundred thirty four students were selected aged 12–15 years from secondary schools in Mosul City, 45 with Class I normal occlusion as control, 44 with Class II malocclusion and 45 with Class III malocclusion, after taking the lateral cephalometric radiographs according to ANB angle. A 20 variables (12 angular and 8 linear) were used in this study to correlate these variables in the three skeletal Classes. Results: No significant sex differences were observed for the majority of angular and linear measurements for the three skeletal types. Anterior cranial base length (S–N) and saddle angle (NSAr) didn’t show significant difference among the three skeletal Classes, the posterior cranial base (S–Ar) was shorter in Class III which indicate the anterior articulation of the mandible. The length of maxillary base (ANS–PNS) was longer in Class II than Class I and III which lead to maxillary prognathism. The body length of the mandible (Go– Pog),effective mandibular length (Ar–Gn) and lower anterior face height was significantly longer in Class III which lead to mandibular prognathism. The SNA angle was significantly smaller in Class III than in the others. SNB and SNPog angles were larger in Class III followed by Class I and then Class II. The gonial angle (Ar–Go– Me) was larger in Class III which acts to increase mandibular effective length. The (N–A–Pog) showed as convex in Class II and concave in Class III. (The U1–PP) angle was larger in Class II followed by Class I and then by Class III. The (L1–MP) angle in Class II and III was significantly smaller than in Class I. Conclusion: Most of the angular and linear measurements indicated that the skeletal differences between the Class I, Class II and Class III are concentrated with in the maxillary and mandibular bases in both the anteroposterior and vertical dimensions and their type of articulation. The dental measurements appear to be compensated with that of skeletal one. Also these variables showed no significant sex differences in the majority of their measurements

Sleep disordered breathing in children with achondroplasia: Part 2. Relationship with craniofacial and airway morphology

We evaluated the craniofacial and airway morphology in children with achondroplasia complicated by snoring and apnea during sleep (AP group) in comparison with children with snoring and apnea during sleep without chromosomal aberrations (adenoid group) and healthy children without sleep disordered breathing or malalignment (healthy group). Lateral cephalograms in 10 children each (four males and six females) in the three groups were analyzed. When the AP and healthy groups were compared, the AP group showed significantly lower values for facial depth, nasal floor length, point A, point pog, and saddle angle (p<0.01) and significantly higher values for mandibular plane angle and gonial angle (p<0.01) regarding craniofacial morphology and significantly lower values for D-AD1, D-AD2, and upper pharynx (p<0.01) regarding airway morphology. When the AP and adenoid groups were compared, the AP group showed significantly lower values for facial depth, nasal floor length, point A, point pog, and saddle angle (p<0.01) and significantly higher values for mandibular plane angle and gonial angle (p<0.01) regarding craniofacial morphology and significantly lower values for D-AD1, D-AD2, and upper pharynx (p<0.05) regarding airway morphology. Thus, the craniofacial/airway morphology in the AP group was characterized by upper airway stenosis, a retruded position of the chin, and an increased mandibular plane angle due to partial early ossification of cranial bones, and an increased lower facial height due to an increased mandibular angle, which may tend to induce sleep snoring and apnea.

ＭＲ画像を重ね合わせた側面頭部Ｘ線規格写真上でのこう筋の観察

The purpose of this study was to observe the morphological relationship between maxillofacial skeleton and masseter by superimposing the masseter image constructed by MR image scanning on the cephalogram. Sixteen subjects with different mandibular plane angle were examined in this study. Cephalogram and MR images of each subject were taken, and the images were input to a computer by using a digitizer. The areas of masseter were selected in each MR scan image which were projected to the mid-sagittal layer of the MR scan images. The synthesized image of cephalogram and masseter was obtained by completely superimposing sagittal images of the masseter with the mid-sagittal-plane MR image on the cephalogram. The inclination of masseter was determined by the center of gravity on the cross-section of masseter. These synthesized images of cephalogram and masseter showed various shapes of masseter according to different mandibular plane angle. The inclination of masseter had a close correlation with some skeletal parameters (mandibular plane angle, ANB, Y-axis, facial angle, saddle angle) of cephalometric analysis. The volume of the masseter also had a close correlation with skeletal parameters (mandibular plane angle, gonial angle, Y-axis). These results revealed that morphometric analysis using synthesized images of cephalogram and masseter is useful, and that the inclination and the volume of masseter may have an influence on the shape of the mandibular bone and its vertical and anteroposterior development.

Cranial base influence on the nasomaxillary complex in Class II division 1 malocclusion (Three dimensional cephalometric study)

Aim: To evaluate the effect of the cranial base on the nasomaxillary complex in class II division 1 malocclusion. Materials and Methods: The study was carried out on a sample of 104 Iraqi subjects in Mosul City aged 18–24 years 53 females and 51 males having class II division 1 malocclusion. Lateral and posteroanterior radiographs were taken for each subject and twenty three measurements were used (Nine angular and fourteen linear). Results of the analysis were the median (NSBa), lateral cranial base (NSCo) and saddle angle (NSAr) showed a significant effect on the inclination of the Frankfort plane from the anterior and posterior cranial base in same direction, For the saddle angle significantly affect the inclination of the Frankfort plane but in the opposite direction while on anteroposterior position of alveolar process of the premaxilla (SNPr) in the same direction. The anterior part (SN), second lateral posterior part (SCo) and depth of cranial base (NBa) significantly affect the maxillary length (ApMax–PNS), upper anterior (N–ANS) and posterior facial height (S–PNS). For the median posterior part (SBa) and first lateral posterior part (SAr) no significant effect on (upper anterior facial height). The anterior cranial base width (GL–GL) showed a significant affect [facial (Zy–Zy), maxillary (J–J) and upper intermolar width (U6–U6)]. While posterior cranial base width (Mas–Mas) was significantly affect [facial (Zy–Zy), maxillary (J–J) and nasal width (Nc–Nc)].Conclusion: The median, lateral cranial base and saddle angles showed correlation with the inclination of the Frankfort plane from the anterior and posterior cranial base. The observed impact of the cranial base widths on the nasomaxillary complex widths were for anterior cranial base width there was a significant effect on bizygomatic, bimaxillary and intermolar width

Effect of changing the saddle angle on the incidence of low back pain in recreational bicyclists.

OBJECTIVE: According to the literature, 30-70% of cyclists suffer from cervical, dorsal, or lumbar back pain. This study was conducted to evaluate one of the possible causes of low back...

A study of the growth changes in facial configuration

In order to explore the growth changes in facial configuration, 160 subjects (80 young adults and 80 children aged 11-12) with normal occlusion were selected for roentgenocephalometric analysis. The present study led to the following conclusions: (a) The ratios of anterior upper to anterior total facial heights, anterior lower to anterior total facial heights, and anterior upper to anterior lower facial heights in both sexes stayed constant around 45, 55, and 81 per cent, respectively. (b) The change in the ratio of the posterior total to anterior total facial heights was mainly due to the greater potentiality of the posterior part of the lower face. (c) The increases of the lower anterior and posterior dental heights were larger than that of the upper anterior and posterior dental heights, respectively. The increases of the upper and lower posterior dental heights were larger than that of the upper and lower anterior dental heights, respectively. (d) On average, the mandibular plane and the occlusal plane tended to rotate forwards with age while the cant of the sella-nasion plane, the Frankfort horizontal plane, and the palatal plane remained fairly unchanged. (e) The saddle angle, the articular angle, and the FNA angle remained relatively stable with age, while the gonial angle and the FNB angle seemed to be age-related. The decrease in the size of the gonial angle might contribute mainly to the flattening tendency of the mandibular growth coincident with general growth. (f) Both the inclination of upper incisor to palatal plane and lower incisor to mandibular plane remained reasonably constant throughout maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

The cranial base in subjects with dental and skeletal Class II.

The aim of this study was to test to what extent the cranial base variations may be involved in Class II facial organization. Using Bonferonni probabilities, cranial base size and shape, and facial divergence were compared in two groups: an experimental group of 45 subjects with dental and skeletal Class II and an homologous control group of 41 subjects with a natural Class I ideal occlusion. In all individuals of the experimental group the Class II molar relationship was at least equal to the width of one premolar and the ANB angle was greater than the value of the mean +2 standard deviations of the ANB in the control group. Spacing and crowding was less than 2 mm at each arch in both groups; all subjects were between 10 and 12 years old. The anterior part of the cranial base (SN length and SNBa angle) was identical in the two groups, but in Class II, cranial base flexure (BaSN angle) was more obtuse (P less than 0.05) and posterior cranial base angle (SBaN) was more acute (P less than 0.01). These variations co-existed in the same group with a more retruded position of the condylar neck in the face (P less than 0.01) favouring per se a post-normal relationship of the mandible to the maxilla. The increased extension of the saddle angle in Class II could not be considered here as related to an hyperdivergent facial pattern since facial divergence was unchanged in Class II. Saddle angle and divergence correlated in Class I (r = 0.40; P less than 0.01), but not in Class II.(ABSTRACT TRUNCATED AT 250 WORDS)

Effectiveness of Wear Plate at the Saddle Support

A theory is presented to analyze the effectiveness of incorporating a wear plate at the saddle support of a cylindrical pressure vessel. The wear plate can be either welded to the vessel or of loose fitting. The theory is based on a contact stress formulation together with the use of a cylindrical shell bending theory for simply supported cylinder. The effectiveness of the wear plate in reducing the peak circumferential saddle-horn stress is quantified by definition of a stress reduction factor. Parametric data are carried out for the saddle angle of 120 deg. From the study, the optimum thickness of the wear plate for three different angular extensions, are obtained.

Common Cycling Injuries

The increasing participation in the athletic forms of bicycling warrants expanded physician attention to the traumatic and overuse injuries experienced by cyclists. The modern bicycle consists of a frame with various components, including handlebars, brakes, wheels, pedals, and gears, in various configurations for the various modes of cycling. For high performance cycling the proper fit of the bicycle is critical. The most efficient method to provide an accurate fit is the Fitkit, but proper frame selection and adjustment can be made by following simple guidelines for frame size, seat height, fore and aft saddle position, saddle angle, reach and handlebar height. The human body functions most effectively in a narrow range of pedal resistance to effort. Riding at too much pedal resistance is a major cause of overuse problems in cyclists. Overuse injuries are lower using lower gear ratios at a higher cadence. Cycling injuries account for 500,000 visits per year to emergency rooms in the US. Over half the accidents involve motor vehicles, and road surface and mechanical problems with the bicycle are also common causes of accidents. Head injuries are common in cyclists and account for most of the fatal accidents. Despite good evidence of their effectiveness, victims with head injuries have rarely worn helmets. Contusions, sprains and fractures may occur throughout the body, most commonly to the hand, wrist, lower arm, shoulder, ankle and lower leg. The handlebar and seat have been implicated in a wide variety of abdominal and genital injuries. Abrasions, lacerations and bruises of the skin are the most common traumatic injuries. Trauma may be prevented or reduced by proper protective safety equipment and keeping the bike in top mechanical condition. Anticipation of the errors of others and practising and adopting specific riding strategies also help to prevent traumatic injuries. Management of overuse injuries in cycling generally involves mechanical adjustment as well as medical management. Neck and back pain are extremely common in cyclists, occurring in up to 60% of riders. Ulnar neuropathy, characterised by tingling, numbness and weakness in the hands is common in serious cyclists after several days of riding. Managing saddle-related injuries or irritations may also involve adjusting seat height, angle and fore and aft position in addition to changing the saddle. Padding in the saddle and shorts play an important part in saddle problems. Saddle-related problems include chafing, perineal folliculitis and furuncles, subcutaneous perineal nodules, pudendal neuropathy, male impotence, traumatic urethritis and a variety of vulva trauma.(ABSTRACT TRUNCATED AT 400 WORDS)

中国大陸におけるモンゴロイドの歯科人類学的研究

The purpose of this study was to evaluate the craniofacial and occlusal characteristics of the inhabitants in China. The material consisted of cephalograms, pantomograms, dental casts and anthropological measurements taken from 517 inhabitants: 416 Han Chinese in Beijing, Shanghai, Guangzhou and Changchun and 101 Mongolians in Hohhot. The data were compared among the above five regions and also with the Japanese data. The findings were summarized as follows: I. Craniofacial characteristics; a) The Han Chinese and the Mongolians showed brachycephaly. b) The inhabitants in Guangzhou showed a tendency of bimaxillary protrusion with a smaller facial height, and the inhabitants in Changchun showed a larger gonial angle with a larger facial height than those of the other regions. c) The Mongolians had a larger value of the saddle angle and of the bi-gonial breadth. d) Compared with the Japanese, their craniofacial complex was characterized by a larger facial angle, smaller mandibular plane angle and a smaller gonial angle. II. Occlusal characteristics; a) The inhabitants in China had a similar tendency in the dental arch form and in the dental trait frequency. b) The inhabitants in Beijing had a larger mesiodistal crown-diameter of the anterior teeth than those in the other regions. c) Compared with the Japanese, their teeth were characterized by a smaller mesiodistal crown-diameter (especially on the upper first molar), higher frequency of shovel-shape and lower frequency of Carabelli's tuberculum.

Functional orthopedic magnetic appliance (FOMA) III—Modus operandi

An intraoral intermaxillary appliance has been developed for the treatment of Class III malocclusions that exhibit midface sagittal deficiency with or without mandibular excess. The functional orthopedic magnetic appliance (FOMA) III consists of upper and lower acrylic plates with a permanent magnet incorporated into each plate. The upper magnet is linked to a retraction screw. The upper magnet is retracted periodically (e.g., monthly) to stimulate maxillary advancement and mandibular retardation. The attractive mode neodymium magnets used in this study produced a horizontal force of 98 gm and a vertical force of 371 gm. Six female Macaca fascicularis monkeys were treated with FOMA IIIs. An additional three animals were treated with sham appliances. After 4 months of treatment, the following results were found: the growth pattern of the cranial base (saddle angle) was not altered; midfacial protraction did occur along a recumbent hyperbolic curve with a horizontal maxillary displacement and an anterosuperior premaxillary rotation; the cumulative protraction of the maxillary complex was initiated at the pterygomaxillary fissure with an additional contribution provided by other circummaxillary sutures (zygomaticomaxillary s., transverse s., premaxillary s.); and inhibition of mandibular length was minimal, but a tendency toward a vertical condylar growth pattern was observed. The interaction between sutural and condylar growth sites appeared biphasic, characterized by an immediate and rapid excitation of the circummaxillary sutures followed by a delayed and slow suppression of the condylar cartilage. Long-term animal and clinical FOMA III studies are recommended.

Natural head position, posture, and prognathism: the Chapman Prize Essay, 1986.

Natural head position and natural head posture are terms which have been used synonymously to describe the spatial relationships of the head with reference to the true vertical, the cervical column, or both. This is confusing, and it would seem logical to ascribe one term to one reference and consider the phenomena separately. For the purposes of this prospective cephalometric survey, natural head position will describe the relationship of the head to the true vertical, while natural head posture will describe the relationship of the head to the cervical column. In order to investigate these two relationships of the head, five groups were formed, three representing horizontal discrepancies selected on ANB differences (class I, II and III dental base relationships) and two representing vertical discrepancies selected on Bjork's posterior angles ('high angle' and 'low angle' groups). Despite the marked differences in 'skeletal' pattern shown between the five groups, the values obtained for the saddle angles (N-S-Ar) showed no significant difference. However, the natural head positions and natural head postures were significantly different (P less than 0.01). Natural head position affected cranial base orientation and this alone produced class II or III effects. Natural head position was also associated with maxillary prognathism whilst natural head posture appeared more closely related to mandibular prognathism. These phenomena may help to explain an apparent class II or III tendency in cases where the saddle angle is normal.

Saddle angle and maxillary prognathism: A radiological analysis of the association between the NSAr and SNA angles: Seppo JärvinenBr. J. Orthod. 11: 209–213, 1984

Saddle angle and maxillary prognathism: A radiological analysis of the association between the NSAr and SNA angles: Seppo JärvinenBr. J. Orthod. 11: 209–213, 1984

Stresses in Saddle‐Supported Ductile‐Iron Pipe

A study of stresses induced in ductile‐iron pipe by saddle supports is described in this article. Experimental data on strain were used to determine the distribution of stress in the vicinity of the saddle. Results indicate that the optimum saddle angle is in the range of 90–120 degrees. The maximum localized stress for pipe with R/t values ≥ 28 can be approximated by the formula σ = k (P/t2) In (R/t), where k = 0.03 ‐ 0.00017 (β ‐ 90) and β is the saddle angle in degrees.

Saddle angle and maxillary prognathism: a radiological analysis of the association between the NSAr and SNA angles.

In cephalometric radiography, two angles have been commonly used, the saddle angle (NSAr) and the SNA angle. The former has been regarded as the cranial base angle, the latter as an indicator of the antero-posterior relation of the maxilla to the cranial base. In this study, a sample of 138 lateral skull radiographs of untreated orthodontics patients aged 7-15 years and analysed. The sample consisted of Angle's Class I, Class II, and Class III malocclusion cases. Means and standard deviations of the NSAr and SNA angles and the S-N and S-Ar lines for different malocclusion groups were estimated, and for each malocclusion group, the model of linear regression (y = bx + a) between the SNA and NSAr angles was computed. The mean of the NSAr angle was significantly larger in the Class II malocclusion group than in the Class III malocclusion group (p less than 0.05). The computed regressions indicated that about 14-40 per cent of the variation of the SNA angle in different malocclusion groups and about 24 per cent in the whole sample could be explained by the variation of the NSAr angle. Because at least a part of the correlation between the NSAr and SNA angles had a topographical causation, the main cause of this topographical correlation probably being the rotation of the S-N plane, the SNA angle was regarded as an unreliable indicator, the use of which can lead to considerable errors.

Relation of the SNA angle to the saddle angle

The degree of the individual facial prognathism, considering the relationship between the SNA and NSAr angles, was studied in a sample of forty-two children with Class I (Angle) malocclusion. A definite relationship was found between the NSAr and SNA angles. When the NSAr angle was large, the SNA angle was relatively small: on the contrary, when the NSAr angle was small, the SNA angle was significantly large. The conclusion was drawn that in persons with Class I malocclusion, a marked part of the variation of the SNA angle is to be explained by the variation of the NSAr angle. Since the value of the SNA angle can be affected by the configuration of the cranial base, it should be used with caution, especially if the value of the NSAr angle is abnormal.

The saddle angle: constancy or change?

Serial cephalometric radiographs of 165 children have been used to analyze age-associated changes in the saddle angle (Ba-S-N). There are mean decreases in this angle of about 5 degrees from birth to 2 years in those with either a Class I or a Class II occlusion; later changes are slight. The mean values tend to be slightly smaller in Class I boys than in those with Class II. Generally, the means are slightly larger in boys than girls but in adults this sex difference is in the reverse direction while remaining slight. It is reasonable to conclude that change is dominant in the first two years. Even after pubescence the angle is not constant but the changes are much smaller. The variability of the angle is greater for Class II than Class I individuals and its variability is greater in girls than boys after 12 years. Almost all the median increments are negative; that is, the flexure of the cranial base decreases with age particularly if the increments begin at the first available radigraph. This tendency is more marked in Class II then Class I occlusion. The increments are markedly variable in each occlusion group with large changes occurring in some individuals. Correlations between the saddle angles at different ages are high; this shows a marked constancy of the relative levels for individuals. The correlations between increments are small; presumably this reflects the small sizes of these increments relative to error terms. In the present group the saddle angle is positively correlated with Ba-N length, but the correlation between the saddle angle and either cranial vault length of stature are near zero. These findings show that there is marked constancy within individuals after the age of 2 years although, as noted earlier, there is marked variability in the size of the angle at particular ages and the serial data for some unusual individuals show large changes that are generally decreases.