Gender Dimorphism of Skeletal Measurements and Dental Angle Classification in Orthodontic Patients.

AIM: The present study aimed to evaluate gender dimorphism of the skeletal and dental angles and measurements among different types of malocclusions in the Population of Jizan, Kingdom of Saudi Arabia (KSA). MATERIALS AND METHODS: Cephalometric data were retrieved from the archived records of 272 dental patients, comprising 134 males and 138 females. Skeletal and dental malocclusions in both the sub-groups were digitally studied. STATISTICAL ANALYSIS: The measurement reliability was assessed using the intra-class correlation coefficient (ICC). Non-parametric Mann-Whitney U tests were performed to evaluate the difference in skeletal and dental parameters between genders. The Chi-square test was done to determine the difference in malocclusion patterns amongst the gender. RESULTS: Statistical significance was noted in dental malocclusion (p-value = 0.003) and facial height, with females having a steeper mandible plan than males. The Sella-nasion-Nasion-Vertical line angles were reported high in females with no statistical significance. Linear cephalometric values were measured higher in males than females, whereas angular values and facial height parameters were lower in females than male. CONCLUSION: Within the limitation of this study, it could be concluded that there is a prominent difference measured in facial profiles of males and females with higher facial height in males. Clinical significance and limitations: These clinical outcomes will help orthodontists to analyze the accurate base angles and points to draft proper treatment plans considering the variation in the profile of males and females.

Diagnostic validity of different gonial angle segmentation for the assessment of mandibular growth direction: A retrospective study.

BACKGROUND: The development of the mandible largely determines the sagittal and vertical lateral appearance. The gonial angle (Articulare-Gonion-Menton, Ar-Go'-Me), as a composite indicator, represents the growth direction of the mandible. We proposed a method based on the Frankfort horizontal (FH) plane and its vertical plane (VFH) to divide the gonial angle into sagittal and vertical components (Articulare-Gonion-VFH / Menton-Gonion-FH, Ar-Go'-VFH / Me-Go'-FH) and to compare the accuracy of diagnosing the development of the mandible and maxillofacial structures with other methods. METHODS: Lateral cephalometric films from 736 volunteers aged 6-30 years were collected and analyzed for cephalometric measurements. Four groups of segmentation-based angle, including the FH-based segmentation (Ar-Go'-VFH / Me-Go'-FH), the SN-based segmentation (Articulare-Gonion- Sellion-Nasion plane' vertical plane/ Menton-Gonion- Sellion-Nasion plane, Ar-Go'-VSN / Me-Go'-SN), the Go'-S based segmentation(Articulare-Gonion-Sellion / Menton-Gonion-Sellion, Ar-Go'-S / Me-Go'-S), and the Go'-N based segmentation (Articulare-Gonion-Nasion / Menton-Gonion-Nasion, Ar-Go'-N / Me-Go'-N), as well as commonly used sagittal and vertical indices were measured. Pearson correlation analysis was used to show the representativeness of different segmentation methods on the mandibular growth direction. RESULTS: As the gonial angle decreased with age, all the segmentation-based metrics decreased. The plane-based segmentation metrics, including Ar-Go'-VFH / Me-Go'-FH, Ar-Go'-VSN / Me-Go'-SN, were superior to the point-based segmentation metrics (Ar-Go'-S / Me-Go'-S, and Ar-Go'-N / Me-Go '-N) in evaluating vertical and sagittal development of the mandible. The sagittal indicators displayed alteration of ramus and condyle, while these vertical indicators responded to the alteration of the mandibular corpus and gonial angle. CONCLUSIONS: The gonial angle should be clinically segmented with planes (including SN plane and FH plane) rather than points (including Go'-S and Go'-N) to assess mandibular development. The FH plane-based segmentation method facilitated chair-side diagnosis of the mandibular growth direction.

Assessment of the maxilla-mandible-nasion angle in normal and aneuploid foetuses in the first trimester of pregnancy.

PURPOSE: This retrospective study aims to determine whether the maxilla-mandible-nasion (MMN) angle can be reliably measured in the first trimester, to describe normal ranges, and to determine if significant changes occur in foetuses with aneuploidies. METHODS: The MMN angle was measured in stored 2D-ultrasound images of 200 normal fetal profiles between 11+0 and 13+6 weeks of gestation. Each image was analyzed by two observers at two independent time points. Bland-Altmann analysis was performed to evaluate the reliability of the measurements. Additionally, the MMN angle was measured on sonograms from 140 aneuploid foetuses. RESULTS: The mean MMN angle in normal foetuses from 11 to 14 weeks of gestation was 15.4°. Reliability of the measurement was high when repeatedly measured by the same observer (ICC = 0.92 and 0.82) and between two observers (ICC = 0.77 and 0.63). Average MMN values in foetuses with trisomy 21, 13, and Turner syndrome were significantly higher than those measured in normal foetuses. The highest differences were observed in foetuses with trisomy 13. Among those, 62% had an MMN angle above the 95th percentile and 92% above the normal mean. CONCLUSION: The MMN angle can be reliably measured in early pregnancy and is abnormal in about 60% of foetuses with trisomy 13.

Evaluation of an automated superimposition method for computer-aided cephalometrics.

OBJECTIVES: To evaluate a new superimposition method compatible with computer-aided cephalometrics and to compare superimposition error to that of the conventional Sella-Nasion (SN) superimposition method. MATERIALS AND METHODS: A total of 283 lateral cephalometric radiographs were collected and cephalometric landmark identification was performed twice by the same examiner at a 3-month interval. The second tracing was superimposed on the first tracing by both the SN superimposition method and the new, proposed method. The proposed method not only relied on SN landmarks but also minimized the differences between four additional landmarks: Porion, Orbitale, Basion, and Pterygoid. The errors between the landmarks of the duplicate tracings oriented by the two superimposition methods were calculated at Anterior Nasal Spine, Point A, Point B, Pogonion, and Gonion. The paired t-test was used to find any statistical difference in the superimposition errors by the two superimposition methods and to investigate whether there existed clinically significant differences between the two methods. RESULTS: The proposed method demonstrated smaller superimposition errors than did the conventional SN superimposition method. When comparisons between the two superimposition methods were made with a 1-mm error range, there were clinically significant differences between them. CONCLUSIONS: The proposed method that was compatible with computer-aided cephalometrics might be a reliable superimposition method for superimposing serial cephalometric images.

Intraoperative Head Slippage with the Head Clamp System Can Occur During Epileptic Surgery.

BACKGROUND: During neurosurgery, we use a head clamp system for firm head fixation. However, we have encountered slippage using the head clamp system, although this has not been adequately studied. In the present study, to increase the reliability of the analysis using a more homogeneous type of patient data, we conducted a prospective study of patients who had undergone epileptic surgery. We examined the potential risk factors for head slippage and postulated that the location of the pins might be important. METHODS: We reviewed and compared the positions of the fixed head of the patients on fused preoperative and postoperative computed tomography images. We measured the distance between the corresponding head pins to determine the association with head slippage. We statistically compared the relationship between each head pin and the nasion-inion line. We also assessed age, sex, body weight, body mass index, surgical position, surgical duration, and craniotomy volume as potential risk factors for slippage. RESULTS: Head slippage was observed in 3 of 21 patients (14%) in the present prospective study. The most caudal head pin position was not associated with head slippage in the present study. However, the center point between the most caudal point and the most cranial point was significant (P = 0.014). A center point between the most caudal and most cranial pins from the nasion-inion line that was >6.5 cm was more likely to result in slippage. CONCLUSIONS: We should consider that head clamp slippage could occur intraoperatively.

Estimation of Risk Factors for Head Slippage Using a Head Clamp System. A Retrospective Study.

BACKGROUND: Although complications have been associated with head clamp systems, few reports have described head slippage. The present study aimed to determine risk factors for head slippage and speculated that the position of head holder pins might be associated. PATIENTS AND METHODS: We reviewed medical records and compared the positions of the pinned heads of patients on fused preoperative and postoperative computerized tomography (CT) images. We measured the distance between corresponding head pins to determine head slippage. Age, sex, body weight, body mass index, surgical position, surgical duration, craniotomy volume, and the relationship between head pins and the nasion-inion (NI) line were statistically compared between patients with and without head slippage. RESULTS: Head slippage in 3 (10%) of 28 patients was significantly associated with the most caudal pin position (p < 0.001) and craniotomy volume (p = 0.036). Receiver operator characteristics curves indicated a cutoff of 4.5 cm from the NI line (sensitivity and specificity, 1.000 and 0.800, respectively). CONCLUSION: Clamped heads can slip during surgical procedures. We found that one head pin should be located within 4.5 cm from the NI line to avoid head slippage.

A Cephalometric Evaluation of Sexual Dimorphism of the Angle Sella-Nasion-Frankfort Horizontal Plane in Different Sagittal Classes of Malocclusion in South Indian Population.

AIMS AND OBJECTIVES: The present study aims to evaluate the gender dimorphism of the angle SN-FH between the sella-nasion (SN) plane and the Frankfort horizontal (FH) plane among the three types of skeletal malocclusion in South Indian population. The objectives included measurement of angle SN-FH, FH to the nasion (NFH), FH to the sella (SFH), and the difference of NFH and SFH (Δ). The null hypothesis was that there exists no variation of the angle SN-FH, NFH, SFH, and Δ between males and females and in the different skeletal relationship of jaws. MATERIALS AND METHODS: Cephalometric data were retrieved from the archived records of 180 patients, comprising 90 males and 90 females, within three subgroups. Class I (60), Class II (20), and Class III (10) in each of the gender class were examined. Student's "t" test was used to analyze means of the gender differences and analysis of variance between subgroups, and significance was set at P < 0.05. RESULTS: The average values obtained from this study for the overall population are 8.06 ± 3.34; for males, it is 7.42 ± 3.62, and for females, it is 8.7 ± 3.48. The gender difference is statistically significant only in Class I malocclusion (0.002). There is no statistical difference between different skeletal classes of malocclusion. CONCLUSION: The null hypothesis is partially rejected for as significant difference is established only for some of the parameters under the study.

Cephalometric Evaluation of Natural Head Position in Lingayat Population of Karnataka.

AIMS AND OBJECTIVES: To ascertain norms in cephalometry for 11- to 13-year-old Lingayat children in natural head position (NHP). MATERIALS AND METHODS: Lateral cephalograms of children were obtained by using fluid level device. We determined the variance in Frankfort horizontal plane (FHP) inclination to extracranial horizontal in NHP. The G*Power, version 20 for Windows was used for analysis. RESULTS: Reduced facial convexity was observed when the analysis was carried out in relation to true horizontal with significant difference of "t" value of 3.05 and percentage difference of 1.1 (P < 0.01) and for girls "t" value of 9.69 and percentage difference of 2.5 (P < 0.001). The highest correlation coefficient for Lingayat boys (r = 0.77) was seen between palatal plane and occlusal plane. We found least correlation coefficient among FHP and Sella-nasion plane (SNP). The coefficient was r = 0.62 and correlation coefficient of r = 0.70 was between FHP and determination coefficient r 2 = 0.38 or 38%. For girls, highest correlation coefficient of r = 0.70 was seen among FHP and palatal plane. CONCLUSION: Conventional study of craniofacial forms of Lingayat children showed the average skeletal pattern as Class II with retrognathic mandible in comparison to Caucasians. However, when seen in NHP by new method of analysis based on the true horizontal, the skeletal model was Class III in comparison to Caucasians.

Long-term impact of pediatric endoscopic endonasal skull base surgery on midface growth.

OBJECTIVE: Cranial base development plays a large role in anterior and vertical maxillary growth through 7 years of age, and the effect of early endonasal cranial base surgery on midface growth is unknown. The authors present their experience with pediatric endoscopic endonasal surgery (EES) and long-term midface growth. METHODS: This is a retrospective review of cases where EES was performed from 2000 to 2016. Patients who underwent their first EES of the skull base before age 7 (prior to cranial suture fusion) and had a complete set of pre- and postoperative imaging studies (CT or MRI) with at least 1 year of follow-up were included. A radiologist performed measurements (sella-nasion [S-N] distance and angles between the sella, nasion, and the most concave points of the anterior maxilla [A point] or anterior mandibular synthesis [B point], the SNA, SNB, and ANB angles), which were compared to age- and sex-matched Bolton standards. A Z-score test was used; significance was set at p < 0.05. RESULTS: The early surgery group had 11 patients, with an average follow-up of 5 years; the late surgery group had 33 patients. Most tumors were benign; 1 patient with a panclival arteriovenous malformation was a significant outlier for all measurements. Comparing the measurements obtained in the early surgery group to Bolton standard norms, the authors found no significant difference in postoperative SNA (p = 0.10), SNB (p = 0.14), or ANB (0.67) angles. The S-N distance was reduced both pre- and postoperatively (SD 1.5, p = 0.01 and p = 0.009). Sex had no significant effect. Compared to patients who had surgery after the age of 7 years, the early surgery group demonstrated no significant difference in pre- to postoperative changes with regard to S-N distance (p = 0.87), SNA angle (p = 0.89), or ANB angle (p = 0.14). Lesion type (craniopharyngioma, angiofibroma, and other types) had no significant effect in either age group. CONCLUSIONS: Though our cohort of patients with skull base lesions demonstrated some abnormal measurements in the maxillary-mandibular relationship before their operation, their postoperative cephalometrics fell within the normal range and showed no significant difference from those of patients who underwent operations at an older age. Therefore, there appears to be no evidence of impact of endoscopic endonasal skull base surgery on craniofacial development within the growth period studied.

A Study on the Evaluation of Pharyngeal Size in Different Skeletal Patterns: A Radiographic Study.

AIM: The aim of this study was to evaluate the upper and lower pharyngeal airway dimensions were affected by different skeletal malocclusions. MATERIALS AND METHODS: Lateral cephalograms of 120 subjects were used to measure the pharyngeal airway and were divided into three groups (each group included 40 subjects) according to ANB angle: Class I (ANB angle 2° ≤ ANB ≤ 4°), Class II (ANB angle(ANB ≥ 6°), and Class III (ANB angle ≤ 0°). Various linear cephalometric airway measurements (14 measurements) were used to evaluate pharyngeal airway at various levels. Statistical analyses were performed Using the ANOVA and student t-test. RESULTS: PNS-ppwl (p < 0.001) and McNamara' lower pharynx dimension (p < 0.05) showed a statistically significant difference between the groups. Two out of 14 variables ie Ba-PNS and t-ppw showed a statistically significant difference between male and female. In both measurements, the difference is significant only in the Class II group with the level of significance being (p < 0.001) in Ba-PNS measurement, and (p < 0.05) in t-ppw measurement. In both measurements males have statistically significant higher mean values than the females. CONCLUSION: The dimensions of pharyngeal structures were not affected by the changes of the ANB angle. The sagittal skeletal pattern does not seem to influence the variations in the upper airway dimension. There was no significant difference in the dimensions of pharyngeal structures among males and females. CLINICAL SIGNIFICANCE: The upper and lower pharyngeal airway dimensions are affected by different skeletal malocclusions can significantly aid in Orthodontic treatment planning.

Control of metopic emissary veins in trigonocephaly surgery. Technical note.

INTRODUCTION: Trigonocephaly with its premature fusion of the metopic synostosis is associated with a risk of cerebral compression and several craniofacial morphological deformations. Numerous surgical techniques have been proposed to enlarge and reshape the forehead. They all carry a risk of bleeding during osteotomies, especially in the region of the superior sagittal sinus (SSS) encased in the early fused suture and of the paired metopic transosseous emissary veins superior to the glabella, which is typical of this type of synostosis. In fact, these paired metopic transosseous veins are often, if not always, the source of major bleeding when torn during the elevation of the frontal flap. TECHNICAL NOTE: A simple technical variant may prevent or at least easily control bleeding in this region during the early phases of the surgical repair. The technical variant to the standard surgical techniques utilized to correct trigonocephaly consists in preserving a triangle of bone above the glabella (about 4 cm at the base and 4 cm in height). The triangle of bone contains the initial segment of the SSS and the emissary metopic veins draining the frontal poles. After removing the frontal flap in a conventional manner, this technical variant allows to detach the veins as well as the SSS from the surrounding bone structures under direct visualization, also in case of vessels running partially encased in the bone. Once the venous structure is detached and hemostasis controlled, this last piece of frontal bone may be removed without unnecessary "iatrogenic" bleeding. CONCLUSION: The propounded procedure does not prolong the surgical time significantly and does not require additional surgical skills or equipment.

Prenasal Thickness, Prefrontal Space Ratio and Other Facial Profile Markers in First-Trimester Fetuses with Aneuploidies, Cleft Palate, and Micrognathia.

OBJECTIVE: To investigate the feasibility and reproducibility of the prenasal thickness (PNT)/nasal bone length (NBL) ratio, maxilla-nasion-mandible (MNM) angle, facial profile line, profile line distance, and prefrontal space ratio (PFSR) in the first trimester of pregnancy, develop normal ranges, and evaluate these markers in abnormal fetuses. METHODS: All measurements were performed on stored images by two operators. Feasibility, interoperator agreement, and prediction intervals were calculated for all measurements. RESULTS: Feasibility was the highest for the NBL (74.3-79.7%) and the MNM angle (75.7-79.05%). Correlation was good for the NBL, the PNT, and the MNM angle (intraclass correlation coefficient 0.706-0.835). Mean difference between operators was the lowest for the PNT and PFSR (0.03-0.08). Measurements in abnormal fetuses showed that the majority of trisomy 21 fetuses had either an absent nasal bone or a shorter NBL. The PNT and PNT/NBL ratio were above the 97.5th centile in one third of the cases. Fetuses with facial clefts or micrognathia showed on average a large MNM angle (multiple of the median 0.96-5.15). CONCLUSION: First-trimester facial markers are feasible. The PNT and PNT/NBL ratio were increased in one third of the trisomic fetuses, and the MNM angle in the majority of fetuses with micrognathia and facial clefts.

Hiding Within the Cracks: Case Report of Rare Sutural Bone Found at the Nasion.

Pathology such as skull fractures can be misdiagnosed in the presence of anatomical variations. One variant that has had little description in the literature are the sutural bones associated with the nasal bones. Herein, we describe a case of a rare sutural bone at the nasion, between the bones of the right nasal, frontal, and maxillary frontal process. To our knowledge, this is the first report of such a variant bone in this location, and such it should be considered by clinicians when evaluating patients for pathology in this region.

Assessment of anterior-posterior jaw relationships in Korean adults using the nasion true vertical plane in cone-beam computed tomography images.

OBJECTIVE: The aims of this study were to investigate a simple method for assessing anterior-posterior jaw relationships via cone-beam computed tomography (CBCT) images taken in the natural head position (NHP) relative to the nasion true vertical plane (NTVP), and measure normative data in Korean adults with normal profiles. METHODS: Subjects were selected from patients presenting for third molar extraction and evaluated as having normal profiles by three examiners. The CBCT images of 80 subjects (39 males, 41 females) were taken in the NHP according to Solow and Tallgren's method. Linear measurements of the A-point, B-point, and Pog were calculated relative to the NTVP. Student's t-test was used to assess sexual differences in these measurements. RESULTS: The mean linear measurements of the A-point, B-point, and Pog relative to the NTVP were 0.18 mm (standard deviation [SD], 4.77 mm), -4.00 mm (SD, 6.62 mm), and -2.49 mm (SD, 7.14 mm) respectively in Korean males, and 1.48 mm (SD, 4.21 mm), -4.07 mm (SD, 6.70 mm) and -2.91 mm (SD, 7.25 mm) in Korean females respectively. There were no statistically significant differences between Korean males and females (p < 0.05). CONCLUSIONS: Three-dimensional CBCT analysis using the NTVP is a simple and reliable method for assessing anterior-posterior skeletal relationships.

Assessment of anterior-posterior jaw relationships in Korean adults using the nasion true vertical plane in cone-beam computed tomography images / 대한치과교정학회지

OBJECTIVE: The aims of this study were to investigate a simple method for assessing anterior-posterior jaw relationships via cone-beam computed tomography (CBCT) images taken in the natural head position (NHP) relative to the nasion true vertical plane (NTVP), and measure normative data in Korean adults with normal profiles. METHODS: Subjects were selected from patients presenting for third molar extraction and evaluated as having normal profiles by three examiners. The CBCT images of 80 subjects (39 males, 41 females) were taken in the NHP according to Solow and Tallgren's method. Linear measurements of the A-point, B-point, and Pog were calculated relative to the NTVP. Student's t-test was used to assess sexual differences in these measurements. RESULTS: The mean linear measurements of the A-point, B-point, and Pog relative to the NTVP were 0.18 mm (standard deviation [SD], 4.77 mm), -4.00 mm (SD, 6.62 mm), and -2.49 mm (SD, 7.14 mm) respectively in Korean males, and 1.48 mm (SD, 4.21 mm), -4.07 mm (SD, 6.70 mm) and -2.91 mm (SD, 7.25 mm) in Korean females respectively. There were no statistically significant differences between Korean males and females (p < 0.05). CONCLUSIONS: Three-dimensional CBCT analysis using the NTVP is a simple and reliable method for assessing anterior-posterior skeletal relationships.

Assessment of Antero-Posterior Skeletal and Soft Tissue Relationships of Adult Indian Subjects in Natural Head Position and Centric Relation.

BACKGROUND: The aim of this study was to verify the intra-individual reproducibility of natural head position (NHP) in centric relation (CR) position, to prove the inter-individual differences in the Frankfort horizontal plane and sella-nasion line compared with the true horizontal line, and to establish linear norms from A-point, B-point, Pog as well as soft tissue A-point, soft tissue B-point, and soft tissue Pog to nasion true vertical line (NTVL) in adult Indian subjects. METHODS: Lateral cephalograms (T1) of Angle's Class I subjects were taken in NHP and with bite in CR. A second lateral cephalogram (T2) of these subjects with ANB angle in the range 1-4° were taken after 1 week using the same wax bite and both the radiographs were analyzed based on six angular parameters using cephalometric software (Do-it, Dental studio NX version 4.1) to assess the reproducibility of NHP. Linear values of six landmarks were taken in relation to NTVL, and the mean values were calculated. A total of 116 subjects were included in this study. RESULTS: When the cephalometric values of T1 and T2 were analyzed, it was found that, the parameters showed a P < 0.001, indicating the reproducibility of NHP in CR. Mean values for point A, point B, Pog and their soft tissue counterparts were also obtained. CONCLUSION: The study proved that NHP is a reproducible and accurate when recorded with the mandible in CR. Linear norms for skeletal Class I subjects in relation to NTVL were established.

Facial profile markers in second- and third-trimester fetuses with trisomy 18.

OBJECTIVES: To evaluate nasal bone length (NBL), maxilla-nasion-mandible (MNM) angle, fetal profile (FP) line, prenasal thickness (PT), prenasal thickness to nasal bone length (PT:NBL) ratio and prefrontal space ratio (PFSR) as markers of trisomy 18 in the second and third trimesters of pregnancy. METHODS: The NBL, MNM angle, FP line, PT, PT:NBL ratio and PFSR were measured retrospectively from stored two-dimensional images or three-dimensional volumes of trisomy-18 fetuses, and were compared with our previously reported normal ranges for euploid fetuses. Additional ultrasound findings were noted at initial routine second-trimester scan and at subsequent advanced ultrasound examination performed after referral for karyotyping. RESULTS: A total of 43 trisomy-18 fetuses were included in the analysis. At initial examination, median gestational age was 21 + 2 weeks. NBL and PT were correlated with gestational age (P < 0.001), but the other markers were not. Mean NBL, MNM angle, PT, PT:NBL ratio and PFSR were 3.76 mm, 16.67°, 4.25 mm, 1.39 and 0.87, respectively. The FP line was zero (normal) in 53.7% of cases and negative (abnormal) in 46.3%. All markers were significantly associated with trisomy 18, with the PT:NBL ratio yielding the highest detection rate (88.4%) followed by NBL (83.7%), MNM angle (56.4%), FP line (46.3%), PT (27.9%) and the PFSR (20.5%) (for a 5% false-positive rate for the continuous variables). Various combinations of the four best markers (NBL, FP line, MNM angle and PT:NBL ratio) yielded detection rates of between 72% and 95%. Structural anomalies were not detected in 22% of fetuses at the initial scan and in 2% at the advanced scan. CONCLUSIONS: The PT:NBL ratio and NBL are robust second- and third-trimester markers for trisomy 18. A negative FP line has a 0% false-positive rate and the potential to differentiate between trisomy 18 and Down syndrome, as in the latter the FP line is often positive. No major anomaly was observed at the initial scan in about a quarter of trisomy-18 fetuses, underlining the role of second-trimester facial marker evaluation.

Fetal facial profile markers of Down syndrome in the second and third trimesters of pregnancy.

OBJECTIVES: To investigate the use of the maxilla-nasion-mandible (MNM) angle and fetal profile (FP) line to assess the degree of midfacial hypoplasia in Down-syndrome fetuses in the second and third trimesters of pregnancy. METHODS: The MNM angle and FP line were measured retrospectively in stored two-dimensional images or three-dimensional volumes of fetuses with Down syndrome. Data collected from January 2006 to July 2013 were retrieved from the digital databases of participating units. The MNM angle was expressed as a continuous variable (degrees) and the FP line as positive, negative or zero. Measurements were obtained from stored images in the midsagittal plane by two experienced examiners and compared with our previously reported normal ranges for euploid fetuses. A MNM angle below the 5(th) centile of the reference range and a positive or negative FP line were considered as abnormal. RESULTS: A total of 133 fetuses with Down syndrome were available for analysis, eight of which were subsequently excluded because of inadequate images. The MNM angle was not influenced by gestational age (P = 0.48) and was significantly smaller in Down-syndrome fetuses than in euploid fetuses (mean, 12.90° vs 13.53°, respectively; P = 0.015). The MNM angle was below the 5th centile for euploid fetuses in 16.8% of fetuses with Down syndrome (P < 0.01). In the cohort of Down-syndrome fetuses, a positive FP line was present in 41.6% of cases (with a false-positive rate (FPR) of 6.3%) and was positively correlated with Down syndrome and gestational age (P < 0.01). There was no case with a negative FP line. In cases of Down syndrome, a positive FP line was correlated with a small MNM angle (P < 0.01). CONCLUSIONS: A small MNM angle and a positive FP line can be regarded as novel markers for Down syndrome. The FP line is an easy marker to measure, has a low FPR, does not require knowledge of normal reference values and has the potential to differentiate between Down syndrome and trisomy 18, as, in the latter, the FP line is often negative.

Comparing the range of µ and ß angles in 6-17-year-old children of Isfahan with normal occlusion.

BACKGROUND: Linear and angular measurements such as A point, nasion, B point (ANB) angle and Wits appraisal index are not accurate enough to evaluate sagittal relationship of the jaws. The aim of this study was to evaluate and compare the range of µ and ß angles in 6-17-year-old children of Isfahan, having normal occlusion. MATERIALS AND METHODS: This was an analytical descriptive study. For this study, 235 cephalometric radiographs of patients who didn't receive orthodontics treatments and based on 13 indexes had normal occlusion, were selected. After tracing of cephalograms, ANB angle, Wits appraisal index, µ angle (resulted from the intersection of AB line and perpendicular line from point A to mandibular plane) and ß angle (resulted from the intersection of AB line and perpendicular line from point A on CB line) were measured. Data was analyzed by t-test, ANOVA and Pierson-Spearman correlation coefficient (P < 0.05). RESULTS: Mean value of µ and ß angles were 17.34 ± 3.47 and 31.7 ± 3.31 and ranged from 8-27 to 21.5-39 respectively. According to t-test, there was a significant difference between two sex groups for µ angle (P = 0.02); however, it was not significant for ß angle. According to Spearman correlation coefficient, there was no significant difference between age and µ angle; however, ß angle was directly and significantly related to age (r = 0.435). There was significant and reverse relationship between µ and ß angles with ANB angle and Wits appraisal index. CONCLUSION: µ and ß angles are reliable and can be used to evaluate the anterior-posterior relationship of the jaws.

A cephalometric study to ascertain the use of nasion as a guide in locating the position of orbitale as an anterior reference point among a population of South Coastal Karnataka.

CONTEXT: To ascertain the use of nasion as a guide in locating the position of orbitale as an anterior reference point in the face-bow transfer records in individuals having different facial types. AIMS: This study evaluated the distance from the nasion to the orbitale using cephalometric measurements to ascertain the use of nasion as a guide in locating the position of orbitale as an anterior reference point in individuals having different facial types among a population of South Coastal Karnataka. SUBJECTS AND METHODS: Anthropometric measurements were made on 61 subjects and they were classified into mesoprosopic, euryprosopic and leptoprosopic facial type groups based upon the prosopic index. Lateral cephalometric radiographs were taken and nasion to orbitale distance was measured. The collected data was tabulated and statistically analyzed. STATISTICAL ANALYSIS USED: The statistical test carried out was the analysis of variance test and correlations were checked for using Pearson's correlation test. RESULTS: The study found the mean distance from nasion to orbitale was 24.25 mm with a standard deviation 4.26 mm. A good correlation was found between prosopic index and nasion to orbitale distance. No statistically significant variation in nasion to orbitale distance in individuals of different facial types was found. CONCLUSIONS: Although, variation exists it was not statistically significant. However, since a large range of measurements were found, prior evaluation using cephalometric radiographs may be necessary in certain individuals.