Nina K. Anderson

Accuracy and reliability of linear cephalometric measurements from cone-beam computed tomography scans of a dry human skull

INTRODUCTION The purpose of this study was to determine the accuracy and reliability of 3-dimensional craniofacial measurements obtained from cone-beam computed tomography (CBCT) scans of a dry human skull. METHODS Seventeen landmarks were identified on the skull. CBCT scans were then obtained, with 2 skull orientations during scanning. Twenty-nine interlandmark linear measurements were made directly on the skull and compared with the same measurements made on the CBCT scans. All measurements were made by 2 operators on 4 separate occasions. RESULTS The method errors were 0.19, 0.21, and 0.19 mm in the x-, y- and z-axes, respectively. Repeated measures analysis of variance (ANOVA) showed no significant intraoperator or interoperator differences. The mean measurement error was -0.01 mm (SD, 0.129 mm). Five measurement errors were found to be statistically significantly different; however, all measurement errors were below the known voxel size and clinically insignificant. No differences were found in the measurements from the 2 CBCT scan orientations of the skull. CONCLUSIONS CBCT allows for clinically accurate and reliable 3-dimensional linear measurements of the craniofacial complex. Moreover, skull orientation during CBCT scanning does not affect the accuracy or the reliability of these measurements.

Preferences for facial profiles between Mexican Americans and Caucasians.

The objective of this study was to determine differences between Mexican American and Caucasian judges in the acceptability of lip protrusion in computer animations of two male and two female persons of Mexican descent. Thirty Caucasians and 30 Mexican Americans of varying age, sex, education, and level of acculturation responded to facial profile computer animations that moved lips from an extreme protrusive to an extreme retrusive position. Judges were asked to complete two tasks: (1) to press the mouse button when the image was perceived to be most pleasing (MP) and (2) to determine the boundaries of a zone of acceptability (ZA) of lip protrusion by pressing the mouse button when the moving image became acceptable and releasing it when the image of the protrusion became unacceptable. In general, Mexican Americans preferred upper or lower lip positions to be less protrusive than did Caucasians. Larger mean ZAs for both upper and lower lip positions with male computer animation images and lower lip position for female computer animation images were found among Caucasians when compared with low-acculturated Mexican Americans. A significant mean difference in midpoint of acceptability (MA) for lip position between Caucasians and low-acculturated Mexican Americans was observed for both upper and lower lip position with female computer animation images.

Changes of pharyngeal airway size and hyoid bone position following orthodontic treatment of Class I bimaxillary protrusion

OBJECTIVES To test the hypothesis that the sagittal position of the anterior teeth has no effect on pharyngeal airway dimension or hyoid bone position and to investigate the influence of orthodontic retraction of the anterior teeth on each section of pharynx and hyoid position. MATERIALS AND METHODS Forty-four Class I bimaxillary protrusion adults, treated with preadjusted appliances and maximum anchorage after extraction of four premolars, were divided into two groups according to their vertical craniofacial skeletal patterns. Pretreatment and posttreatment variables were compared using paired t-test, and the relationship between pharyngeal airway size and dentofacial variables was analyzed using Pearson correlation coefficient. The changes of pharyngeal airway size and hyoid position after treatment were compared between two groups using independent t-test. RESULTS Upon retraction of the incisors, the upper and lower lips were retracted by 2.60 mm and 3.87 mm, respectively. The tip of upper incisor was retracted by 6.84 mm and lower incisor retracted by 4.95 mm. There was significant decrease in SPP-SPPW, U-MPW, TB-TPPW, V-LPW, VAL, C3H, and SH (P < .05). No statistically significant different changes were observed in the dentofacial structures, pharyngeal airway, and hyoid position between the two groups after the treatment. There was a significant correlation between the retraction distance of lower incisor and the airway behind the soft palate, uvula, and tongue. CONCLUSIONS The pharyngeal airway size became narrower after the treatment. Extraction of four premolars with retraction of incisors did affect velopharyngeal, glossopharyngeal, hypopharyngeal, and hyoid position in bimaxillary protrusive adult patients.

The Perception of Children's Computer-Imaged Facial Profiles by Patients, Mothers and Clinicians

OBJECTIVE To demonstrate the usefulness of a new imaging system for comparing the morphometric bases of childrens self-perception of their facial profile with the perceptions of their mothers and treating clinicians. MATERIALS AND METHODS Rather than choosing among a series of static images, a computer imaging program was developed to elicit a range of acceptable responses or tolerance for change from which a midpoint of acceptability was derived. Using the method of Giddon et al, three profile features (upper and lower lips and mandible) from standardized images of 24 patients aged 8- 15 years were distorted and presented to patients, parents, and clinicians in random order as slowly moving images (four frames per second) from retrusive and protrusive extremes. Subjects clicked the mouse when the image became acceptable and released it when it was no longer acceptable. Subjects responded similarly to a neutral facial profile. RESULTS Patients and their mothers overestimated the protrusiveness of the mandible of the actual pretreatment profile. Consistent with related studies, mothers had a smaller tolerance for change in the soft tissue profile than the children or clinicians. The magnitudes of the childrens self-preference and preferred change in a neutral face were also significantly correlated. Both patients and mothers preferred a more protrusive profile than that of the actual or neutral face for the patient and neutral face. CONCLUSION Imaging software can be used with children to compare their preferences with those of parents and clinicians to facilitate treatment planning and patient satisfaction.

Differences in Pain, Psychological Symptoms, and Gender Distribution among Patients with Left- vs Right-Sided Chronic Spinal Pain

OBJECTIVE To determine pain levels, function, and psychological symptoms in relation to predominant sidedness of pain (right or left) and gender in patients being treated for chronic spinal pain. DESIGN Prospective cohort study. PATIENTS Patients with chronic neck or low back pain undergoing a nerve block procedure in a specialty pain medicine clinic. INTERVENTIONS/OUTCOMES: Patients completed the Hospital Anxiety and Depression Scale and the Brief Pain Inventory just prior to the procedure. Pain history and demographic variables were collected from a chart review. Chi-square, Pearson correlations, and multivariate statistics were used to characterize the relationships between side of pain, gender, pain levels, pain interference, and psychological symptoms. RESULTS Among 519 subjects, men with left-sided pain (N = 98) were found to have significantly greater depression and anxiety symptoms and worse pain-related quality of life (P < 0.01), despite having similar pain levels as men with right-sided pain (N = 91) or women with left- or right-sided pain (N = 289). In men, psychological symptoms had a significantly greater correlation with pain levels than in women (P < 0.01). CONCLUSION In this sample, men with left-sided spinal pain report worse quality of life and more psychological symptoms than women. These data provide clinical evidence corroborating basic neuroscience findings indicating that the right cerebral hemisphere is preferentially involved in the processing of pain and negative affect. These data suggest that men appear more right hemisphere dominant in pain and affect processing. These findings have implications for multidisciplinary assessment and treatment planning in men.

Methodological challenges when performing a systematic review

Well-conducted systematic reviews can provide a foundation upon which to base educational curricula, practice guidelines and healthcare policy. We aim to provide an overview of important methodological issues that need to be addressed during the five phases of performing a systematic review. 1. The specific problems to be addressed by the systematic review need to be formulated as clear, unambiguous and structured question/s. 2. Literature from multiple resources should be searched to avoid publication biases, as positive outcomes are more likely to be published than null/negative results. 3. The quality of selected articles should be assessed using a checklist, while the reliability of graders, as well as the quality of the checklist, needs to be established a priori. 4. Statistical heterogeneity needs to be assessed to determine if a meta-analysis is appropriate to pool the data. If not, a narrative synthesis of the evidence/overall findings needs to be performed within a clinical context.

Editor's Summary and Q&A: Accuracy of reconstructed images from cone-beam computed tomography scans

INTRODUCTION The aim of this study was to determine whether 2-dimensional (2D) images produced from cone-beam computed tomography (CBCT) images taken with an iCAT scanner (Imaging Sciences International, Hatfield, Pa) can substitute for traditional cephalograms. METHODS Lateral and frontal cephalograms were taken of a radiographic phantom with known dimensions. Landmarks on the 2D images were traced and measured manually by 2 examiners and then digitally in Dolphin 10 (Dolphin Imaging Sciences, Chatsworth, Calif) by the same examiners. A CBCT scan was taken of the phantom, and orthogonal and perspective projections were created from the scans. Frontal and lateral cephalograms were created by using the 3-dimensional function in Dolphin 10, digitized into Dolphin, and traced by the same 2 examiners. Linear measurements were compared to assess the accuracy of the generated images from the CBCT scans. RESULTS Measurements on the orthogonal projections were not significantly different from the actual dimensions of the phantom, and measurements on the perspective projections were highly correlated with those taken on standard 2D films. CONCLUSIONS By constructing a perspective lateral cephalogram from a CBCT scan, one can replicate the inherent magnification of a conventional 2D lateral cephalogram with high accuracy.

Facial aesthetics and perceived need for further treatment among adults with repaired cleft as assessed by cleft team professionals and laypersons

Sir, We read with great interest the recent article by Foo et al . (2013), on ‘Facial aesthetics and perceived need for further treatment among adults with repaired cleft as assessed by cleft team professionals and laypersons’. However, we would like to express the following comments regarding the methodology of this study. 1. The sample of cleft patients used for this study is not homogeneous and included 44 bilateral and 33 unilateral cases with cleft lip and palate, as well as one patient each with isolated cleft lip, isolated cleft palate and a submucosal cleft palate. A study …