The Frankfort horizontal as a basis for cephalometric analysis

Perception of maxillary incisor inclination and its correlation with dental cephalometric measurements

OBJECTIVE

To correlate the clinical perception of maxillary incisor inclination from photographs of the smiling face with cephalometric measurements, using conventional incisor axis reference points and crown reference points.

DESIGN

Cross-sectional study.

SETTING

Department of Orthodontics, School of Dentistry, University of Lisbon (Portugal).

PARTICIPANTS

Eight orthodontists.

METHODS

The perception of maxillary incisor inclination of 47 female patients (mean age 23.4 ± 1.5 years) was evaluated by eight orthodontists. The participants' photographs (smiling frontal, smiling three-quarter and smiling profile) were shown to each assessor and a continuous visual analogue rating scale was used to assess the perception of maxillary incisor inclination. Pearson's correlation and linear regression were calculated between each cephalometric measurement and the perception of incisor inclination.

RESULTS

Anatomical crown inclination measurements U1ac-FH (r = 0.854; P < 0.01) and U1ac-SN (r = 0.845; P < 0.01) had the highest correlation values with the assessors' perception of maxillary incisor inclination. Conventional incisor axis measurements showed the lowest correlation values (r = 0.668-0.756).

CONCLUSION

Cephalometric measurements of the labial surface of the anatomical crown of the maxillary incisors showed the strongest correlations with the clinical perception of maxillary incisor inclination from photographs. For optimal aesthetics, the inclination of the labial surface of maxillary incisor crown should be evaluated.

Facial Analysis of Patients with Unilateral or Bilateral Cleft Lip and Palate Using 3D Stereophotogrammetry

OBJECTIVES

To evaluate the quantitative values of linear and angular facial anthropometrics in patients with unilateral cleft lip and palate (UCLP) and compare them with those of patients with bilateral cleft lip and palate (BCLP) using three-dimensional (3D) facial imaging.

DESIGN

Retrospective, observational, and cross-sectional study.

SETTING

Hospital for Rehabilitation of Craniofacial Anomalies/USP (HRAC/USP).

PATIENTS/ PARTICIPANTS

In total, 61 non-syndromic patients with CLP who underwent multidisciplinary treatment and rehabilitated with a prosthesis were enrolled and divided into those with UCLP (G1; n = 31) and those with BCLP (G2; n = 30).

INTERVENTION

Facial images were captured using a 3D camera after landmarks were marked on each patient's face. The software evaluated linear and angular parameters. Statistical tests were applied. Significance was determined as P < 0.05.

MAIN OUTCOME MEASUREMENTS

Overall, 22 linear and 13 angular measurements were evaluated.

RESULTS

The nasal length (P = 0.08), middle third of the face (P = 0.06), base nose width (P < 0.001), nasal root width (P < 0.001), nasal tip angle (P = 0.018), philtrum width (P < 0.001), lower face width (P = 0.039) and midfacial depth (P = 0.040) were significantly higher in G2; the upper cutaneous lip height was significantly higher in G1. Sexual dimorphism was observed except for linear measurements (linear distance between the labiale superius and labiale inferius landmarks, nasal root width, and upper cutaneous lip length) and angular measurements.

CONCLUSIONS

G2 had a greater length and width of nose and nasal root, nasal tip angle, philtrum width, and lower face width, midfacial depth, and midface third than G1. These findings also revealed the presence of sexual dimorphism.

SIDS plane: A simple and innovative alternative to Frankfurt horizontal plane

AIMS AND OBJECTIVES

To derive a new horizontal plane which can be a suitable alternative to Frankfurt horizontal plane (FH plane).

MATERIALS AND METHODS

200 pre-treatment lateral roentogenic cephalograms from patient records in the department of orthodontics and dentofacial orthopaedics were traced. The landmarks were identified and marked and the measurements were carried out. Patients with all skeletal relationships were included in the study. The angle formed between the lines connecting anatomic porion, orbitale and machine porion was measured and tabulated. Dimorphism between the genders if any was also evaluated.

RESULTS

The mean angulation between the planes from the anatomic porion to orbitale to machine porion (PoA-Or-PoM) in our sample is 3.14 ± 2.17°. PoA to Or to PoM angulation for males is 2.57° and for females is 3.4°.

CONCLUSIONS

SIDS plane also called as derived FH plane given here is a reliable and easily reproducible alternative to the FH plane.

Predictive Equation for Construction of Anatomic Porion with Machine Porion as Reference Point

AIM

The aim of the study was to find a relationship between anatomic porion (PoA) and machine porion (PoM) and to construct PoA with the help of machine porion.

METHODOLOGY

About 200 pretreatment lateral roentgenic cephalograms were used for the study. Perpendicular distances of PoA and PoM were measured from Sella-Nasion (SN) plane and SN perpendicular plane. The results were tabulated. With the help of statistical analysis, predictive equation was derived to construct PoA and PoM. p-value was set at p < 0.05.

RESULTS

Anatomic porion distance from SN was 24.35 ± 3.96 and from SN perpendicular was 12.89 ± 4.56. Distance of PoM from SN was 22.46 ± 4.20 and from SN perpendicular was 16.76 ± 4.89. Sexual dimorphism was also seen.

CONCLUSION

There is a relationship between the PoM and PoA, thus, PoA, which is more reliable, can be constructed with the help of PoM, which is easy to reproduce.

CLINICAL SIGNIFICANCE

To overcome the inherent limitations of PoA and PoM, the present study aimed to find a relationship between the two so as to easily construct PoA that is more reliable while taking advantage of the ease of reproducibility of PoM.

A Preliminary Study of a Novel Reference Plane of the Head: Comparing With the True Horizontal Plane

A new reference plane of the head, based on soft tissue landmarks and suitable for clinical analysis and soft tissue measurements, is needed. We recently discovered a novel reference plane, that is, the COs plane, which was formed by bilateral Lateral Canthus and bilateral Otobasion Superius and might be horizontal at the natural head position (NHP). In this study, we investigated the angles between the COs plane and the true horizontal (TrH) plane while sitting and standing, aiming to explore whether the new plane could be used as a substitution for the reference plane in clinical practice. Briefly, 26 volunteers were enrolled. Their sitting and standing NHP were recorded using the 3dMDface system. In the pitch axis, the mean angle of COs/TrH was 0.29 degrees and 0.41 degrees for sitting and standing positions, respectively, showing no statistical difference ( P >0.05). However, in the roll axis, the mean angle of COs/TrH for sitting position and standing positions was 1.08 and 1.33 degrees ( P <0.05), which was considered to be the result of habitual canting of the head. Moreover, there were no significant differences between the sitting and standing NHP, considering the COs/TrH angles ( P >0.05). To sum up, we concluded that the COs plane could be used as a reliable reference plane in certain soft tissue analysis and clinical applications.

Cephalometric determinants of facial attractiveness: A quadratic correlation study

INTRODUCTION

This research aimed to determine the nonlinear correlation between lateral cephalometric measurements and facial attractiveness, evaluated in the frontal and profile views. A quadratic correlation was studied, in which the vertex of the function indicates the cephalometric value corresponding to the maximum attractiveness.

METHODS

Frontal and profile facial attractiveness of 60 patients with Class I (n = 20), Class II (n = 20), or Class III malocclusion (n = 20) aged 18-35 years without previous orthodontic treatment was evaluated by 14 laypersons (7 men and 7 women) with a visual analog scale. Soft- and hard-tissue measurements were collected on lateral cephalometric radiographs. Pearson and nonlinear quadratic correlations between the attractiveness of the face and cephalometric measurements were calculated. Maximum attractiveness values (MxAt) were determined for the significant cephalometric variables.

RESULTS

Significant quadratic correlations were found between frontal facial attractiveness and the following variables: Ls-SnPog' (r = 0.45; MxAt = 3.1 mm), Li-SnPog' (r = 0.41; MxAt = 3.8 mm), the ANB angle (r = 0.42; MxAt = 0.2°) and MPA (r = 0.51; MxAt = 31.9°). Profile attractiveness correlated nonlinearly with Ls-SnPog' (r = 0.42; MxAt = 3.2 mm), Li-SnPog' (r = 0.41; MxAt = 3.9 mm) and MPA (r = 0.46; MxAt = 32.4°).

CONCLUSIONS

Significant quadratic correlations were found between facial attractiveness and cephalometric measurements, which were stronger than linear correlations. The maximum attractiveness points indicated a tendency for laypeople to consider a more protrusive lower lip and an ANB angle lower than the norm as the most attractive.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

None.

2D and 3D cephalometric measurements.

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P < .05) and petrous-occipital (β = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P < .001) and occipitomastoid synchondrosis (β = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P < .001), anterior intraoccipital synchondrosis (β = -368.47; P < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

An approach to define newborns´ sniffing position using an angle based on reproducible facial landmarks

BACKGROUND

The neutral or sniffing position is advised for mask ventilation in neonates to avoid airway obstruction. As definitions are manifold and often unspecific, we wanted to investigate the reliability and reproducibility of angle measurements based on facial landmarks that may be used in future clinical trials to determine a hypothetical head position with minimal airway obstruction during mask ventilation.

METHODS

In a prospective single-center observational study, 2D sagittal photographs of 24 near-term and term infants were taken, with five raters marking facial landmarks to assess interobserver agreement of those landmarks and angle δ, defined as the angle between the line parallel to the lying surface and the line crossing Subnasale (Sn) and Porion' (P'). Angle δ was assessed in sniffing (δ^sniff ) and physiologic (δ^phys ) head position, the former based on a published, yet poorly defined head position where the tip of the nose aligns to the ceiling with the head in a supine, relaxed mid-position.

RESULTS

Infants had a mean (SD) gestational age of 37.3 (2.3) weeks. Angle δ could be determined in all 48 images taken in either the sniffing or the physiological head position. Interobserver correlation coefficient was 98.6 for all measurements independent of head position. Angle δ^sniff was 90.5° (5.7) in the sniffing position.

CONCLUSIONS

This study provides a new measuring technique using an angle that is reproducible and reliable and may be used in future studies to correlate head position with airway obstruction.

Variation between natural head orientation and Frankfort horizontal planes in orthognathic surgery patients: 187 consecutive cases

The purpose of this study was to assess the relationship between the Frankfort horizontal (FH) and natural head orientation (NHO), their correlation between patients' malocclusion, and the impact of counterclockwise rotation (CCW) on the FH-NHO angle variation after orthognathic surgery. An evaluation of 187 consecutive patients was performed at the Maxillofacial Institute (Teknon Medical Center, Barcelona). FH-NHO° was measured pre- and postoperatively at 1 and 12 months, after three-dimensional (3D) superimposition using a software (Dolphin®). Patients were classified as follows: 3.2%, 48.7% and 48.1%, class I, II and III, respectively. Baseline FH-NHO° was significantly positive for patients with dentofacial deformities (2.73°±4.19 (2.12-3.33°, P<0.001). The impact of orthognathic surgery in FH-NHO° was greater in class II when compared with class III patients, with a variation of 2.04°±4.79 (P<0.001) and -1.20°±3.03 (P<0.001), respectively. FH-NHO° increased when CCW rotational movements were performed (P=0.006). The results of this study suggest that pre- and postoperative NHO differs from FH in orthognathic patients. The angle between FH and NHO is significantly larger in class III than in class II patients at baseline, which converges after orthognathic surgery when CCW rotation is performed. Therefore, NHO should be used as the real horizontal plane when planning for orthognathic surgery.

Agreement and Reliability of Median Neurodynamic Test 1 and Resting Scapular Position

Objective

The purposes of this study were to determine whether there are differences between the dominant and nondominant arms for the Median Neurodynamic Test 1 (MNT 1); whether there are differences between men and women on the MNT 1; the reliability of an assessment of resting scapular position; the reliability of the MNT 1; and the frequency and percentage of sensory responses that are present during the MNT 1 in the asymptomatic population.

Methods

This was a reliability and agreement study. It included asymptomatic students enrolled in the college of health professions and the college of nursing at a university. The Mann-Whitney U was used to determine whether there were any differences between the dominant and nondominant sides and between sexes for elbow extension range of motion and for sensory responses on the numeric pain rating scale when performing the MNT 1. A χ² analysis was used to determine whether there were any differences between sexes and between dominant and nondominant upper extremities for sensory-response location, sensory-response type, and structural differentiation for raters 1 and 2. The intraclass correlation coefficient (ICC_2,3) was used to determine the intertester and intratester reliability for the degrees of elbow extension attained during testing.

Results

Reliability for degrees of elbow extension and strength of the sensory response was excellent (ICC_2,3 ˃ 0.75) and substantial (κ ≥ 0.68), respectively. Resting scapular position and all other components of the MNT 1 demonstrated statistically significant side-to-side differences and κ values ranging from 0.23 to 0.88.

Conclusion

Elbow extension and magnitude of sensory response are reliable components of the MNT 1 that are not different between the dominant and nondominant sides in the asymptomatic population.

Reliability of the beighton score and impact of generalized joint mobility and resting scapular position on Median Neurodynamic Test 1

INTRODUCTION

There is a lack of understanding of the impact of generalized joint mobility, joint hypermobility, and resting scapular position on neurodynamic testing of the median nerve. The objectives of the study were to determine: 1) the reliability of the Beighton score (BS) with and without the cutoff score for general joint hypermobility (GJH); 2) if there are differences in the Median Neurodynamic Test 1 (MNT 1) based on the Beighton cutoff score for GJH; 3) if there are differences in the MNT 1 based on an assessment of resting scapular position; 4) if there are relationships between the BS with and without the cutoff score for GJH, resting scapular position, and MNT 1.

METHODS

Testing was performed by two testers at two-time intervals at least 1 week apart. The population of interest was healthy asymptomatic adults. The outcome measures included the BS, resting scapular position, and MNT 1.

RESULTS

Intraclass correlation coefficients (ICC_2,1) were 0.52 for intertester reliability at visit 1 and 0.86 at visit 2, with intratester reliability of 0.88 for Tester 1 and 0.71 for Tester 2 for the BS. Intertester prevalence-adjusted bias-adjusted kappa (PABAK) values for the Beighton GJH cutoff scores were 0.80-0.84 and 0.80 to 0.92 for intratester reliability. There were no statistically significant differences or relationships for any of the other variables of interest.

CONCLUSION

Joint mobility and resting scapular position are not confounding variables when performing MNT 1 in an asymptomatic population.

The Reliability and Influence of Body Position on Acoustic Pharyngometry and Rhinometry Outcomes

OBJECTIVES

The aim of this cross sectional study was to analyze the method error and reliability in acoustic pharyngometry and rhinometry and to analyze the difference between standing and sitting position in acoustic pharyngometry and rhinometry.

MATERIAL AND METHODS

The sample comprised 38 healthy subjects (11 men and 27 women) as part of a control group in another study. The subjects underwent repeated measures of acoustic pharyngometry and rhinometry in standing and sitting position. Upper airway dimensions in terms of volume, minimum cross-sectional areas (MCA) and distances were evaluated using the Eccovision® Acoustic Pharyngometer and Rhinometer. Method error and reliability were analyzed using paired t-test, Dahlberg's formula and the Houston reliability coefficient, and differences between body positions were analyzed using paired t-test.

RESULTS

There was no systematic error in the repeated measures except for the distance to MCA in the left nostril in sitting position (P = 0.041). The method error for the pharyngometry ranged between 0.001 to 0.164 cm/cm2/cm3 and the reliabity was 0.99. The method error for rhinometry ranged between 0.001 to 0.37 cm/cm2/cm3 and the reliability between 0.99 to 1. Difference between standing and sitting position was found only in the pharyngeal airway in terms of volume (P = 0.025) and mean area (P = 0.009) with smaller airway in sitting position.

CONCLUSIONS

The results indicate that acoustic pharyngometry and rhinometry are reliable methods to perform repeated measures of the upper airway dimensions especially in the standing mirror position. It may be essential to perform the measures with the patient positioned in the same body position each time.

Effect of thoracic and pelvic anteroposterior diameters on spinal sagittal alignment

PURPOSE

This study aimed to analyze the effect of the thoracic anteroposterior diameter (TAPD) and pelvic anteroposterior diameter (PAPD) on global sagittal alignment in asymptomatic patients with normal sagittal alignment.

PATIENT SAMPLE

The study investigated 2042 adult patients who initially presented at our hospital with a hip and knee problem without history of symptoms related to the entire spine. Only 57 patients with normal global sagittal alignment (C2-7 sagittal vertical axis (SVA) and C7-S1 SVA of <10 mm) were considered.

METHODS

The whole-spine standing lateral radiographs were obtained to analyze the following parameters: pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracic inlet angle (TIA), T1 slope, cervical spinal parameters (angle of C0-2, C2-7, and C0-7), TAPD, and PAPD. Statistical analysis was performed using Pearson correlation coefficients and multiple regression analyses.

RESULTS

All the parameters showed a normal distribution. TAPD had a significant relationship with thoracic kyphosis (TK; r = 0.458), TIA (r = 0.677), and C0-2 angle (r = 0.294) but no significant relationship with T1 slope and other cervical parameters. PAPD had a significant relationship with PI (r = 0.309) and PT (r = 0.463) but no significant relationship with LL, SS, and TK. The multiple regression analysis showed that TIA = 21.974 + 0.405 (TK) + 0.188 (TAPD) (p < 0.0001).

CONCLUSIONS

TAPD and PAPD are associated with TIA, TK, C0-2 angle, PI, and PT, all of which act as key factors in spinal sagittal alignment. Although they did not directly correlate with other cervical parameters, T1 slope, and LL, TAPD and PAPD might have indirect effects on cervical and lumbar spinal sagittal alignment through their relationships with TIA, TK, and PI.

Improvement in cervical lordosis and sagittal alignment after vertebral body sliding osteotomy in patients with cervical spondylotic myelopathy and kyphosis

OBJECTIVE

Vertebral body sliding osteotomy (VBSO) is a safe, novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. Another advantage of VBSO may be the restoration of cervical lordosis through multilevel anterior cervical discectomy and fusion (ACDF) above and below the osteotomy level. This study aimed to evaluate the improvement and maintenance of cervical lordosis and sagittal alignment after VBSO.

METHODS

A total of 65 patients were included; 34 patients had undergone VBSO, and 31 had undergone anterior cervical corpectomy and fusion (ACCF). Preoperative, postoperative, and final follow-up radiographs were used to evaluate the improvements in cervical lordosis and sagittal alignment after VBSO. C0-2 lordosis, C2-7 lordosis, segmental lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and Japanese Orthopaedic Association scores were measured. Subgroup analysis was performed between 15 patients with 1-level VBSO and 19 patients with 2-level VBSO. Patients with 1-level VBSO were compared to patients who had undergone 1-level ACCF.

RESULTS

C0-2 lordosis (41.3° ± 7.1°), C2-7 lordosis (7.1° ± 12.8°), segmental lordosis (3.1° ± 9.2°), and C2-7 SVA (21.5 ± 11.7 mm) showed significant improvements at the final follow-up (39.3° ± 7.2°, 13° ± 9.9°, 15.2° ± 8.5°, and 18.4 ± 7.9 mm, respectively) after VBSO (p = 0.049, p < 0.001, p < 0.001, and p = 0.038, respectively). The postoperative segmental lordosis was significantly larger in 2-level VBSO (18.8° ± 11.6°) than 1-level VBSO (10.3° ± 5.5°, p = 0.014). The final segmental lordosis was larger in the 1-level VBSO (12.5° ± 6.2°) than the 1-level ACCF (7.2° ± 7.6°, p = 0.023). Segmental lordosis increased postoperatively (p < 0.001) and was maintained until the final follow-up (p = 0.062) after VBSO. However, the postoperatively improved segmental lordosis (p < 0.001) decreased at the final follow-up (p = 0.045) after ACCF.

CONCLUSIONS

Not only C2-7 lordosis and segmental lordosis, but also C0-2 lordosis and C2-7 SVA improved at the final follow-up after VBSO. VBSO improves segmental cervical lordosis markedly through multiple ACDFs above and below the VBSO level, and a preserved vertebral body may provide more structural support.

Use of the orbito-occipital line as an alternative to the Frankfort line

Frankfort horizontal line, the line passing through the orbitale and porion, is one of the most widely used intracranial landmarks in cephalometric analysis. This study investigated the use of the orbito-occipital line extending from the orbitale to the external occipital protuberance as a novel horizontal line of the skull for substituting the Frankfort horizontal line. We evaluated the reproducibility of the new landmark and measured the angle between the orbito-occipital line and the Frankfort line. This study was conducted on 170 facial computed tomography (CT) scans of living adults from the Department of Plastic Surgery. After three-dimensionally reconstructed images were obtained from facial CT, the porion, orbitale, and external occipital protuberance were indicated by two observers twice. The angles between the orbito-meatal line (inferior orbital rim to porion; the Frankfort line) and the orbito-occipital line (inferior orbital rim to external occipital protuberance) were measured. There was no significant intraobserver or interobserver bias. The overall angle between the Frankfort line and orbito-occipital line was −0.5°±2.2° (mean±standard deviation). There was no statistically significant difference among side and sex. This study demonstrated good reproducibility of a new landmark—the external occipital protuberance—tested to replace the porion. The orbito-occipital line is a reliable, reproducible, and easily identifiable line, and has potential as a novel standard horizontal line to replace or at least supplement the Frankfort line in anthropological studies and certain clinical applications.

Selected Orthodontic Principles for Management of Cranio-Maxillofacial Deformities

An understanding of fundamental orthodontic principles involving diagnosis, treatment planning, and clinical strategies is essential for achieving successful outcomes in the treatment of craniofacial patients, particularly cleft lip/palate. This article focuses on: customizing a mandibular dental arch form using the WALA ridge; accurately diagnosing the maxillary skeletal transverse dimension (cusp to cusp/fossa to fossa); coordinating the upper dental arch with the lower; using a smiling profile and glabella vertical to assess anteroposterior jaw position; and leveling the mandibular curve of Spee while considering the lower one-third of the face. These concepts influence treatment outcomes to the extent they are used.

Prediction of late displacement of the globe in orbital blowout fractures

PURPOSE

To establish a linear measuring method in computed tomographic (CT) images to predict the displacement of the globe late after orbital blowout fracture.

METHODS

Subjects were retrospectively included. Inclusion criteria were as follows: (1) adult subjects (≥18 years old at the time of trauma); (2) unilateral orbital medial-wall and/or floor fractures; (3) CT examination at least 30 days after trauma. Exclusion criteria were as follows: (1) facial or orbital fracture extending to other parts of the orbit than medial-wall and/or floor; (2) history of orbital or ocular abnormality other than the orbital trauma; (3) severe ocular trauma accompanied by the orbital trauma; (4) orbital fracture treated surgically before the CT examination. A co-ordinate system was built based on the orbital CT scans. Displacements of orbital walls, displacement of the globe and relative location of the fracture site were measured. Correlations between the variables were investigated.

RESULTS

Ninety-nine per cent of fracture sites of the medial wall and 100% of fracture sites of the floor were posterior to the centre of the unaffected globe. The affected globe moved significantly medially (p < 0.001) and backwards (p < 0.001) in pure medial-wall fracture; backwards (p < 0.001) and downwards (p = 0.017) in pure floor fracture; and medially (p < 0.001), backwards (p < 0.001) and downwards (p < 0.001) in medial-wall and floor fractures. Displacement of the globe was correlated with displacements of the orbital walls, and the regression formulae were therefore fitted. Application of the formulae revealed that the same extent of orbital wall displacement caused more displacement of the globe in female patients than in male patients.

CONCLUSIONS

A linear measuring method in a three-dimensional co-ordinate system was established to identify the displacements of orbital walls and the displacement of the globe in orbital blowout fractures. The regression formulae generated in this study might be used in clinical practice to predict late displacement of the globe by measuring the displacements of orbital walls.

Contribution of facial components to the attractiveness of the smiling face in male and female patients: A cross-sectional correlation study

INTRODUCTION

Esthetic improvement is a key motivator in undergoing orthodontic treatment. This study aims to quantify the contribution of the smile and other facial components to the overall esthetics of attractiveness.

METHODS

The attractiveness of 60 subjects (30 men, 30 women), aged 18-35 years, before orthodontic treatment, was retrospectively evaluated by 8 laypersons using the Visual Analog Scale. Pearson and stepwise correlations were calculated between the attractiveness of the smiling face and the attractiveness of facial components; namely the smile, nose, eyes, hair, chin, eyebrows, and skin.

RESULTS

A strong correlation between the face and smile attractiveness was found (r = 0.71) for the whole sample. No significant correlations were found between attractiveness and the other facial components. When divided by gender, the smile (r = 0.70) and the eyes (r = 0.51) correlated with the attractiveness of the smiling face for men. For women, the face registered a significant correlation with the smile (r = 0.83) and the skin (r = 0.37).

CONCLUSIONS

In general, smile attractiveness was strongly correlated with the attractiveness of the smiling face, which is the only significant component. For men, the smile was responsible for 49% of the variation in the attractiveness of the smiling face, the eyes for 22%, and the hair for 6%. For women, 69% of the variation in facial attractiveness could be attributed to smile.

Will different sagittal and vertical skeletal types relate the soft tissue thickness: A study in Chinese female adults

Facial reconstruction is a classical technique in forensic anthropology to reestablish the contours of the soft tissues over the skull. The accurate facial soft tissue data plays an essential role in forensic facial reconstruction. However, according to previous studies, various skeletal types might relate to different thickness in facial soft tissue. Until now, there are few publications focusing on the relationship between facial soft tissue thickness (FSTT) and different skeletal types, and none of them analyze the FSTT according to various sagittal and vertical skeletal types. The aim of this study was to testify the possible existence of correlations between FSTT and different skeletal types. In order to exclude interference from age, sex, ethnicity and body mass index (BMI) factors, we collected lateral projection X-rays data of 270 Chinese female aged 19-26 years with nomal BMI and divided them into various skeletal groups. Soft tissue thickness measurements were mainly based on 10 anthropological landmarks of the skull and statistics were analyzed on the basis of different skeletal types. The greatest differences were observed in the upper lip region of maxilla and the mental region of mandible. The concave and hypodivergent skull types showed the thickest soft tissue in maxillary region, and the convex and hypedivergent skull types showed the thickest soft tissue in the mental region. This study provided a database for FSTT according to various skeletal types in Chinese female population, and our current studies demonstrated that considering various skeletal types will improve the accuracy of facial reconstruction.

Etiology of Cleft Lip Lower Lip Deformity: Use of an Objective Analysis to Measure Severity

OBJECTIVE

Measure lower lip thickness and eversion in patients with cleft lip and palate (CLP) and maxillary hypoplasia. The specific aims were to (1) compare lower lip thickness/eversion in patients with CLP to noncleft controls with maxillary hypoplasia, (2) determine differences between patients with unilateral CLP (UCLP) and bilateral CLP (BCLP), and (3) document changes in the lower lip that occur with Le Fort I advancement.

DESIGN

Retrospective case-control study.

SETTING

Tertiary care center.

PATIENTS/PARTICIPANTS

Patients with available pre- and postoperative CT scans and 2D lateral photographs who had a Le Fort I advancement between 2009 and 2017. There were 32 patients with CLP (17 females; mean age 17.7 ± 1.9 years) and 33 noncleft controls (21 females; mean age 18.8 ± 2.6 years).

MAIN OUTCOME MEASURES

Lower lip thickness and eversion.

RESULTS

Patients with CLP and maxillary hypoplasia have a significantly thicker lower lip (P = .019) and outward rotation of the vermilion border (P = .003) compared to noncleft controls. The lower lip was significantly thicker in patients with BCLP than in those with UCLP (P = .035). Lower lip thickness and rotation did not change after maxillary advancement.

CONCLUSIONS

Patients with CLP and maxillary hypoplasia have a thicker and more everted lower lip than noncleft controls. Patients with BCLP have a significantly thicker lower lip than those with UCLP. Strain of the lower lip musculature appears to be an important contributor to the development of the cleft lip lower lip deformity.

Theoretical Basis for Virtual Skull Orientation According to Three-Dimensional Frankfort Horizontal Plane for Computer-Aided Surgical Simulation

PURPOSE

Computer-aided surgical simulation (CASS) is an evolving technology which has significantly affected surgical correction of dentofacial deformities, a key step of which is orientation of the virtual skull model to allow for analysis and treatment planning. Explored in this study is the coplanarity of a 3-dimensional Frankfort horizontal plane (3D FHP).

MATERIALS AND METHODS

The 122 17.0 cm field-of-view cone-beam computed-tomogram (CBCT) scans were oriented to a 3D FHP using right porion, right orbitale, and left orbitale. The distance between the 3D FHP and left porion was then measured. The 18 CBCT scans were found to have external fiducial markers which were used for orientation into natural head position (NHP). The distance between left porion and a true horizontal plan coincidental with the right porion was measured. Concordance reliability measures were calculated to compare NHP to 3D FHP.

RESULTS

The average distance of left porion to 3D FHP was found to be -0.107 mm (SD = 1.148), and the average distance from the coincidental left porion in NHP was found to be 0.846 mm (SD = 2.611). Concordance reliability calculations shows little consistency between the 2 methods of orientation (P = 0.838).

CONCLUSIONS

The data shows coincidence between left porion and 3D FHP. Orientation of the virtual skull model according to 3D FHP offers a quick and easy method for this important step in CASS. Further study is needed for evaluation of this method in vivo.

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 r² = 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.

Skeletal-versus soft-tissue-based cephalometric analyses: is the correlation reproducible?

OBJECTIVES

Dentofacial deformities can be analyzed by skeletal and soft tissue cephalometric analysis (CA). The aim was to evaluate the difference in reproducibility between both methods.

MATERIALS AND METHODS

Lateral cephalograms of 112 patients (65 females and 47 males, 27.7 ± 9.0 years) were oriented in natural head position (NHP) and digitized. The distances of skeletal (SNA, SNB, SnPog) and soft tissue (A', B' and Pog') landmarks relative to the respective norm values and the angles between the Nasion Sella line (NSL) and Frankfurt horizontal (FH) to NHP were measured for statistical evaluation and compared with respective data of an adult control group (CG) with class I occlusion and harmonic facial balance.

RESULTS

The mean differences (mm ± SD) of skeletal and soft tissue landmarks were -2.4 ± 4.4 (A), -7.0 ± 9.3 (B), -6.3 ± 11.2 (Pog), -0.9 ± 1.8 (A'), -4.7 ± 6.2 (B'), and -6.1 ± 7.8 (Pog'), respectively. Pearsons's correlation (r) between the measurements of SNA/A', SNB/B' and SNPog/Pog' were r = .158 (p = .092), r = .662 (p < .001) and r = .655 (p < .001), respectively. The mean (±SD) angles between NSL and FH to NHP were -9.8° ± 5 and 0.0° ± 3.9, respectively.

CONCLUSION

Variability of cranial-based measurements could give a possible explanation for the high variation and the low reproducibility of skeletal cephalometric analysis with soft tissue measurements. Soft-tissue cephalometric analysis would probably improve facial analysis and treatment planning.

Using the zygomatic arch as a reference line for clinical applications and anthropological studies

PURPOSE

The Frankfurt line is the most frequently and widely used reference line in cephalometric analysis, but has shortcomings including the difficulty of landmark identification. This study investigated using the superior border of the zygomatic arch as a new external bony landmark, including measuring the angle between the new reference line and the Frankfurt line.

METHODS

Facial computed tomography scans were obtained from 170 patients (100 males and 70 females) hospitalized at Konkuk University Chungju Hospital. After three-dimensional reconstruction, the locations of the porion and the inferior orbital rim and the superior border of the zygomatic arch were identified twice by two observers using software. A horizontal line parallel to the superior border of the zygomatic arch was established. The angle between the Frankfurt line and new reference line was then measured on each side.

RESULTS

There was no significant intraobserver or interobserver bias. The angle between the Frankfurt line and the superior border of the zygomatic arch was 4.5° ± 2.5° (mean ± SD), and it was somewhat larger in females than males, but the difference was not statistically significant.

CONCLUSIONS

This study demonstrated the good reproducibility of the location of the superior border of the zygomatic arch and found that the angle between the new reference line and the Frankfurt line is relatively constant. The superior border of the zygomatic arch therefore has potential as an alternative reference line to the Frankfurt line in specific clinical applications and anthropological studies, since it is a more accessible bony landmark on the external skull.

Asymmetric Protrusion of the Midface in Young Adults

PURPOSE

This study evaluated midfacial asymmetry using an alternative method that involved comparing bilateral patterns of the zygomaticomaxillary prominence in a young adult population.

MATERIALS AND METHODS

Three-dimensional reconstructed images based on computed tomography scans of 100 Koreans (mean age, 24.7 years) were evaluated with reference to lines spaced at 30° intervals and radiating from the center of an interporion line in a superior view. The surface inclination of the zygomaticomaxillary region was quantified on the same reference lines using a 3-dimensional ruler.

RESULTS

The 30°-interval line (at the level of the zygomaticotemporal suture) was longer on the left side than the right side in both males and females, whereas the left 60°-interval line (at the level of the zygomaticofrontal suture) was longer in females. Comparing the surface protrusion revealed that the zygomaticomaxillary region was more prognathic and inflated on the left side.

CONCLUSION

Functional deviations are considered to be causes of asymmetric craniofacial growth. Postnatal growth allometry across the circummaxillary sutures as elucidated by this study could be useful information in craniofacial surgery.

Influence of the Occipital Orientation on Cervical Sagittal Alignment: A Prospective Radiographic Study on 335 Normal Subjects

Cervical sagittal alignment is considered to have a special role in the pathogenesis and evaluation of cervical diseases. Previous studies have demonstrated that cervical sagittal alignment is correlated with thoracolumbar and pelvic alignments. As the direct anatomical structures connect to the cervical region, however, no parameters in the occiput have been reported to be intimately related to the alignment of the cervical spine. A retrospective radiographic study of 335 individuals (182 males and 153 females) between 18 and 60 years of age was performed between January 2007 and January 2016. The occipital incidence (OI), occipital slope (OS), occipital tilt (OT), C0-C2 angle, C2-C7 angle, C0-C7 angle, T1 slope and thoracic kyphosis were measured in every individual. The mean values of the occipital parameters of the cohort were 34.6° ± 3.1° for OI, 23.4° ± 7.4° for OS, and 11.8° ± 3.3° for OT. OI was constant throughout three age groups. No significant differences were noted between males and females. In addition, strong correlations were found between the occipital parameters and cervical parameters. The occipital orientation was an important factor that influenced the cervical sagittal alignment.

Optimal antero-posterior position of the maxillary central incisors and its relationship to the forehead in adult African American females

OBJECTIVES

To determine an optimal anteroposterior (AP) position of the maxillary central incisors and their relationship to the forehead in adult African American (AA) females.

MATERIALS AND METHODS

Smile profile photographs of 150 AA females were acquired and divided into an optimal control group (N = 48) and a study group (N = 102) based on the position of the maxillary central incisors, as judged by a panel of orthodontists and orthodontic residents. The AP position of the maxillary central incisors and the forehead inclination (FI) were measured relative to Glabella vertical (GV). A two-sample t-test was used to compare the incisor AP position and the FI between the two groups. Linear regression was used to quantify the relationship between the incisor AP position and the FI.

RESULTS

In all groups, the maxillary incisors were anterior to GV. However, a significant difference was found in the incisor AP position between the groups (8.58 ± 3.96 mm for the control group and 11.2 ± 4.48 mm for the study group; P = .001). Furthermore, the control group demonstrated a positive association between the optimal AP position of the maxillary central incisors and FI ( P < .0001).

CONCLUSIONS

GV is a reliable landmark with which to access the AP maxillary incisor position in AA females. The optimal AP position of the maxillary central incisors is significantly associated with FI; the greater the FI, the more anterior the optimal maxillary incisor position. A prediction equation to determine the optimal position of the maxillary incisors relative to GV for AA females is proposed.

Measurement of Intra-Orbital Structures in Normal Chinese Adults Based on a Three-Dimensional Coordinate System

PURPOSE OF THE STUDY

This study was to establish a three-dimensional (3D) coordinate system and to study the normal dimensions of intra-orbital structures in Chinese adults.

MATERIALS AND METHODS

One hundred and forty-five adult Chinese were selected from patients who had undergone cranio-facial computed tomography scans with diagnosis other than orbital or ocular abnormality. An orbital 3D coordinate system was built on the basis of the scans. Morphological variables of intra-orbital structures were measured in this coordinate system. Bilateral symmetry, sexual dimorphism, and correlations between variables were investigated.

RESULTS

No evident laterality was found in bilateral intra-orbital structures. The distance from the center of the eyeball to the prechiasmatic groove, the length of the optic nerve, and the thickness of rectus extraocular muscles were larger in males than in females. No sex-related difference was observed in the anteroposterior diameter of the eyeball or the exophthalmometric value. The exophthalmometric value was found to be related to the anteroposterior diameter of the eyeball, whereas the y-coordinate of the center of the eyeball had no correlation with the anteroposterior diameter of the eyeball. The optic nerve length was closely correlated to the distance from the center of the eyeball to the prechiasmatic groove.

CONCLUSIONS

The 3D coordinate system and measurement method established in this study can be applied to the standardization of orbital morphometry. The measurements obtained from normal Chinese adults may provide reference values for the morphology of intra-orbital structures.

[Natural head position's reproducibility on photographs]

INTRODUCTION

The purpose of this study is to evaluate the reproducibility of natural head position with time on profile photographs.

MATERIALS AND METHODS

Our sample is composed of 96 students (20-30 years old) at the department of dentistry of Saint Joseph University in Beirut. Two profile photographs were taken in natural head position about a week apart.

RESULTS

No significant differences were found between T0 and T1 (E = 1.065°).

DISCUSSION

Many studies confirmed this reproducibility with time. Natural head position can be adopted as an orientation for profile photographs in orthodontics.

Surgical overreduction and hyperlordotic fusion of C1-C2 joint are associated with cervical sagittal malalignment

INTRODUCTION

Previous studies have shown that hyperlordotic C1-C2 fusion was related to postoperative subaxial kyphosis. However, most of the patients in these studies were complicated with rheumatoid arthritis (RA). Moreover, no studies have specifically evaluated the relationship between C1-C2 fusion angle and cervical sagittal vertical axis (cSVA), T1 slope or cranial tilt (CRT) after posterior C1-C2 fusion. This study aimed to investigate the cervical sagittal alignment in non-RA patients following posterior C1-C2 fusion and the correlation between C1-C2 fusion angle and postoperative cervical sagittal alignment.

MATERIALS AND METHODS

From August 2004 to December 2015, twenty-eight consecutive patients with an average age of 39.2 years (range 6-70 years) who underwent posterior C1-C2 fusion from a single institution were enrolled. The mean follow-up period was 30.7 months (range 12-77 months). Angles of Oc-C1, C1-C2, C2-C3 and C2-C7, cSVA, T1 slope and CRT were measured in lateral cervical radiographs in neutral position before surgery and at the final follow-up.

RESULTS

C1-C2 angle significantly increased from 13.6° ± 12.4° to 22.0° ± 8.1° at the final follow-up (P < 0.001). A significant decrease was found both in Oc-C1 and C2-C7 angles from pre-operation to the final follow-up (P < 0.001 and P = 0.011, respectively). Moreover, cSVA and CRT dramatically increased from pre-operation to the final follow-up (P < 0.001). C1-C2 fusion angle was significantly associated with Oc-C1, C2-C7 angle, cSVA and CRT at the final follow-up. A significant correlation was also observed between postoperative change of C1-C2 angle and that of Oc-C1, C2-C7 angle, cSVA and CRT.

CONCLUSIONS

Apart from decreased subaxial lordosis, posterior C1-C2 fusion in hyperextension may also lead to kyphotic change of atlanto-occipital alignment and increased tilting forward of the cervical spine. Therefore, intraoperative overreduction of C1-C2 angle and hyperlordotic C1-C2 fusion should be avoided to maintain the physiologic cervical sagittal alignment.

Diagnosis and treatment planning of orthodontic patients with 3-dimensional dentofacial records

INTRODUCTION

Cephalometrics has been the foundation of orthodontic diagnosis for many years. However, for many orthodontic patients, a lateral cephalogram might not be necessary. The aim of this study was to compare the diagnosis and treatment planning agreement between standard records and nonradiographic 3-dimensional (3D) dentofacial photogrammetry records.

METHODS

Twenty patients had standard orthodontic records taken for their treatment as well as extraoral and intraoral 3D images. Twelve evaluators examined the standard records and then completed diagnosis and treatment planning questionnaires. They repeated the process 4 to 6 weeks later by using 3D photographic images along with the panoramic radiographs. Each evaluator also evaluated 2 random orthodontic cases twice with each method to evaluate consistency within each method. At the end of study, each evaluator was asked to complete a survey to document his or her experiences with the 3D photogrammetry method. Descriptive and kappa statistics were used to determine the agreement.

RESULTS

Most diagnosis parameters had fair agreement between the methods and within each method. Skeletal and dental relationships had excellent agreement between and within the methods as well as most treatment decisions such as the need for extractions and surgery. Most evaluators (91.7%) thought that cephalometric x-rays would be needed only some of the time in diagnosis and treatment planning. Most evaluators (83.33%) thought that cephalometric radiographs are not needed in patients with a Class I ± a quarter cusp with crowding or spacing.

CONCLUSIONS

Most diagnostic decisions had fair agreement within and between the 2 methods. The decision to extract and the need for orthognathic surgery had excellent agreement between the cephalometric and photogrammetric methods. The majority of examiners agreed that patients with Class I malocclusions ± a quarter cusp with no obvious skeletal discrepancy can be diagnosed and planned without a cephalometric radiograph.

An Evaluation of Benchmarks for Esthetic Orientation of the Occlusal Plane

PURPOSE

This patient study was designed to measure the validity of both the horizontal and Camper's planes, which are used as benchmarks to reestablish the sagittal orientation of the occlusal plane angles in dental rehabilitation.

MATERIALS AND METHODS

Profile digital photographs were made of the first 100 consenting dentate patients as they closed on an occlusal plane analyzer while maintaining natural head posture. Using a digital screen protractor, three angles were measured: the occlusal plane angle relative to the horizontal plane, and the angle between the occlusal plane and Camper's plane from both the superior and inferior borders of the tragus of the ear.

RESULTS

The angle between the occlusal plane and the horizontal reference plane for the 100 patients ranged from -8.72° to +18.08° (mean +3.25°); the angle between the occlusal plane and Camper's plane, from the superior border of the tragus to the ala of the nose demonstrated a range from -8.49° to +15.16° (mean +3.03°); and the angle between Camper's plane, from the inferior border of the tragus to the ala of the nose and the occlusal plane demonstrated a range from -15.57° to +9.15° (mean -4.09°).

CONCLUSIONS

Occlusal plane angles measured in this patient population with natural dentitions demonstrated a relatively small mean deviation from both the horizontal plane and Camper's plane when using the superior border of the tragus as the distal reference point, but the range was quite broad and could result in unacceptable occlusal plane angles in many patients undergoing dental rehabilitation.

CLINICAL IMPLICATIONS

Both Camper's plane and the horizontal reference plane may be acceptable initial reference planes for oral rehabilitation, but additional anatomic and esthetic parameters are required for verification of an esthetically pleasing occlusal plane angle.

Sequential alignment change of the cervical spine after anterior cervical discectomy and fusion in the lower cervical spine

PURPOSE

The cervical spine has a linear chain of correlation or reciprocal relationship regionally (within the cervical spine) and globally (head to whole spine). The purpose of this study was to assess the sequential alignment change of the regional and global cervical spine after two-level anterior cervical discectomy and fusion (ACDF) performed on the lower cervical spine.

METHODS

This study included 61 patients (mean age 56 ± 8.6 years; range 35-70 years) who underwent ACDF at C5-6-7 with a plate-cage construct and whose C-spine neutral lateral radiographs showed an identical degree of horizontal gaze (occipital slope) peri-operatively. We compared the change in cervical curvature from the occiput to C7 with the absolute value (slope angle) and relative value (between two different slopes). We also investigated the correlated change in multiple angular parameters according to the change in the occipital slope.

RESULTS

The occipital slope was significantly correlated with the value of the C1-slope (r = 0.33) and C2- slope (r = 0.51). The value of the center of the sellar turcica-C7 sagittal vertical axis (St-SVA) was very closely related to the C1-slope (r = -0.83), C2-slope (r = -0.8), C2-7 angle (r = -0.43), and C2-5 angle (r = -0.46). The amount of angular change at the surgical level (C5-7A) was 5.8° (2.9° -> 8.5°), and the sum of the change in the C5-slope and C7-slope was 6° (3.1° + 2.9°). In general, the C2-5 angle decreased about 3°, in proportion to the upward inclination of C5-slope (3.1°), because the C2-slope was fixed. However, patients who showed improvement in cervical alignment (greatly increased C5-7 lordosis or greatly decreased St-SVA after surgery) often had upper cervical slope change (C1-s and C2-s).

CONCLUSIONS

The ACDF procedure itself can induce regional slope change (C5-s and C7-s) directly at the surgical level and can also influence upper cervical slope change (C1-s and C2s) indirectly. Then the change in the upper cervical spine can induce a change in the St-CVA and spino-cranial angle (SCA).

Natural head position: An overview

Cephalometrics has given us a different perspective of interpreting various skeletal problems in the dentofacial complex. Natural head position (NHP) is a reproducible, physiologically determined aspect of function. To determine NHP, a horizontal or vertical reference line outside the crania was used, but preference was given generally to the horizontal. Various intra and extracranial cephalometric horizontal reference planes have been used to formulate diagnosis and plan individualized treatment for an integrated correction of the malocclusion cephalometrics is constantly undergoing refinements in its techniques and analyses to improve the clinical applications. Even though various methods for establishing NHP have been proposed, still it remains a challenge to the clinicians to implement the concept of NHP thoroughly in all the stages of treatment because of practical difficulties in the clinical scenario.

Factors determining cervical spine sagittal balance in asymptomatic adults: correlation with spinopelvic balance and thoracic inlet alignment

BACKGROUND CONTEXT

Based on the previous studies, cervical lordosis (CL) is a parameter influenced by thoracic kyphosis (TK); however, the correlations still remain unclear. Few studies have analyzed the correlations between the cervical spine lordosis and global spinopelvic balance. To date, there has been no study focused on the factors determining cervical spine sagittal balance.

PATIENT SAMPLE

Seventy-seven asymptomatic volunteers without the history of symptoms related to whole spine.

OUTCOME MEASURES

Statistical significance of correlations of radiographic parameters on cervical spine and whole-spine standing lateral radiograph.

PURPOSE

To analyze the factors determining cervical spine sagittal balance, including global spinopelvic balance and thoracic inlet (TI) alignment in asymptomatic adults.

STUDY DESIGN

A prospective radiographic study.

METHODS

Cervical and whole-spine standing lateral radiographs were taken to analyze the following parameters: spinopelvic parameters pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), and TK; TI parameters thoracic inlet angle (TIA) and T1 slope; and cervical spine parameters C0-C2, C2-C7, and C0-C7 angles and cervical tilting. Statistical analysis was performed using the Pearson correlation coefficients and multiple regression analysis.

RESULTS

All the parameters showed a normal distribution. There was a significant sequential linkage between PI and SS (r=0.653), SS and LL (r=0.807), LL and TK (r=-0.516), and TK and C0-C7 angle (r=-0.322). There was a significant relationship between TK and T1 slope (r=0.351) but no significant relationship between TK and TIA. There were significant sequential relationships between TIA and T1 slope (r=0.694), T1 slope and C2-C7 angle (r=-0.624), and C2-C7 and C0-C2 angles (r=-0.547). T1 slope was the only parameter that demonstrated a significant correlation with both SP and TI parameters. A linear regression model showed that T1 slope had a stronger relationship with TIA (r=0.694) than TK (r=0.351).

CONCLUSIONS

T1 slope was a key factor determining cervical spine sagittal balance. Both spinopelvic balance and TI alignment have a significant influence on cervical spine sagittal balance via T1 slope, but TIA had a stronger effect than TK. An individual with large T1 slope required large CL to preserve physiologic sagittal balance of the cervical spine. The results of the present study could serve as baseline data for further studies on the cervical spine sagittal balance in various clinical conditions including the surgical reconstruction of lordosis.

Cranial-base morphology in adults with skeletal Class III malocclusion

INTRODUCTION

The objectives of this study were to clarify the characteristics of cranial-base morphology in adults with skeletal Class III malocclusion and investigate factors relating to the establishment of a skeletal Class III malocclusion.

METHODS

Initial lateral cephalograms of women were examined. Subjects with an ANB angle of 0° to 4°, normal overjet and overbite, and a Class I molar relationship were classified as Class I (n = 86). Those with an ANB angle less than -1°, a Wits appraisal less than 2 mm, a negative overjet, and a Class III molar relationship were the Class III group (n = 86) in this study. Angular, linear, and coordinate measurements were made. Multivariate analysis of variance and the Student t test were used to analyze significant differences between the 2 groups. Discriminant analysis, logistic regression analysis, and decision analysis were used to identify which cranial-base and maxillomandibular variables influenced the establishment of a skeletal Class III malocclusion.

RESULTS

The Class III group had smaller values for NSBa, SeSBa, FH-SSe, and FH-SBa. Sphenoidale and basion were more inferior and anterior than those of the Class I group. There was no difference in the anterior and posterior cranial-base lengths between the groups. Greater mandibular length was the first major characteristic in the Class III group, followed by smaller values for SeSBa and NSBa.

CONCLUSIONS

Cranial-base morphology in adults with a skeletal Class III malocclusion is different from that in a skeletal Class I malocclusion. Smaller cranial-base angles, steeper posterior cranial bases, more inferiorly positioned sphenoidale, and more anteriorly positioned basion are major characteristics of skeletal Class III malocclusions. These characteristics play important roles in the establishment of a skeletal Class III malocclusion.

The Frankfurt horizontal plane as a reference for the implantation of gravitational units: a series of 376 adult patients

BACKGROUND

The in-line combination of adjustable differential pressure valves with fixed gravitational units is increasingly recommended in the literature. The spatial positioning of the gravitational unit is thereby decisive for the valve opening pressure. We aimed at providing data on factors contributing to primary overdrainage and underdrainage of cerebrospinal fluid (CSF), with special attention paid to the implantation angle of the gravitational unit.

METHODS

Weretrospectively analyzed the postoperative course of 376 consecutive patients who received a ventriculoperitoneal shunt with a proGAV valve. The incidence of both primary CSF overdrainage and underdrainage was correlated with the implantation angle of the gravitational unit in regard to the Frankfurt horizontal plane and the patients' general parameters.

RESULTS

Primary overdrainage was found in 41 (10.9 %) patients. Primary underdrainage was found in 113 (30.1 %) patients. A mean deviation of 10° (±7.8) for the gravitational unit in regard to the vertical line to the Frankfurt horizontal plane was found. In 95 % of the cases the deviation was less than 25°. No significant correlation between the implantation angle and the incidence of overdrainage or underdrainage of CSF was found. The patients' age and having single hydrocephalus entities were identified as factors significantly predisposing patients to overdrainage or underdrainage.

CONCLUSION

The implantation of the gravitational unit of the proGAV valve within a range of at least 10° in regard to the vertical line to the Frankfurt horizontal plane does not seem to predispose patients to primary overdrainage or underdrainage in ventriculoperitoneal shunting. The plane may serve as a useful reference for the surgeon's orientation.

Evaluation of the soft tissue treatment simulation module of a computerized cephalometric program

Objective:

The purpose of this study is to compare the accuracy of the treatment simulation module of Quick Ceph Studio (QCS) program to the actual treatment results in Class II Division 1 patients.

Design:

Retrospective study.

Materials and Methods:

Twenty-six skeletal Class II patients treated with functional appliances were included. T0 and T1 lateral cephalograms were digitized using QCS. Before applying treatment simulation to the digitized cephalograms, the actual T0-T1 difference was calculated for the SNA, SNB, ANB angles, maxillary incisor inclination, and protrusion and mandibular incisor inclination and protrusion values. Next, using the treatment simulation module, the aforementioned values for the T0 cephalograms were manually entered to match the actual T1 values taking into account the T0-T1 differences. Paired sample t-test were applied to determine the difference between actual and treatment simulation measurements.

Results:

No significant differences were found for the anteroposterior location of the landmarks. Upper lip, soft tissue A point, soft tissue pogonion, and soft tissue B point measurements showed statistically significant difference between actual and treatment simulation in the vertical plane.

Conclusion:

Quick Ceph program was reliable in terms of reflecting the sagittal changes that would probably occur with treatment and growth. However, vertical positions of the upper lip, soft tissue pogonion, soft tissue A point, and soft tissue B point were statistically different from actual results.

Is it possible to evaluate the parameters of cervical sagittal alignment on cervical computed tomographic scans?

STUDY DESIGN

Retrospective study.

OBJECTIVE

The purpose of this study was to analyze the relationship of the parameters of cervical sagittal alignment between those obtained from cervical CT and those obtained from radiography, as well as to determine which parameter would help predict physiological lordosis of the cervical spine.

SUMMARY OF BACKGROUND DATA

Sagittal balance in the cervical spine is as important as the pelvic incidence and is related to the concept of T1 slope. However, many articles including this article based on unclear cervical x-ray radiographs could weakly explain the parameters. To overcome the fundamental limitation of x-ray radiographs, Hallym University Sacred Heart Hospital reported the strong correlation between T1 slope and cervical lordosis on the cervical dimensional CT scans like result by checking by the cervical x-ray radiographs.

METHODS

A retrospective analysis of data from 50 asymptomatic adults in whom both cervical CT scans and cervical radiograph were obtained at the same time. The T1 slope, Cobb angle C2-C7, neck tilt, and thoracic inlet angle (TIA) obtained from the CT scans and radiographs were assessed.

RESULTS

The T1 slope on x-ray was significantly correlated with the T1 slope on CT. The mean of the T1 slope on x-ray was larger than the mean of the T1 slope on CT (3.3° ± 6.1°). More cervical spine lordosis was evident on the cervical radiograph than on the cervical CT scan (5.93° ± 9.0°). No significant difference was seen between the TIA on x-ray and the TIA on CT (TIA on x-ray - TIA on CT, -0.1 ± 7.6, P = 0.959).

CONCLUSION

This difference may be due to the differing effect of gravity upon the spine between the upright versus the supine position. Accordingly, TIA and T1 slope may be used as a guide for the assessment of sagittal balance of the cervical spine.

Constancy of the angle between the Frankfort horizontal plane and the sella-nasion line: a nine-year longitudinal study

OBJECTIVE

To investigate the constancy of the angle between the Frankfort horizontal plane (FH) and the sella-nasion line (SN) using longitudinal data.

MATERIALS AND METHODS

Longitudinal lateral cephalometric data of 223 children (116 girls and 107 boys) from 6 to 14 years of age were used. The angle between FH and SN (SNFH), the distance from FH to the nasion (NFH), the distance from FH to the sella (SFH), and the differences between the NFH and SFH (Δ) were also measured. All data were analyzed statistically using independent t-tests and mixed-effect regression model analysis.

RESULTS

The mean SNFH values showed some minor fluctuations, ranging from 9.26° to 9.74° in girls and 8.45° to 8.95° in boys. The mean NFH and SFH values gradually increased according to age irrespective of sex. There were statistically significant differences by sex for all measurements at several ages. The annual change in SFH and Δ showed sexual dimorphism.

CONCLUSIONS

There are variations among individuals in the angle between the FH and SN. However, within an individual, the angle does not vary significantly over time during the observation period.

Randomized controlled trial of a car safety seat insert to reduce hypoxia in term infants

OBJECTIVE

To test the hypothesis that a foam plastic insert that allows the infant head to rest in a neutral position in sleep may prevent obstruction of the upper airway and thus reduce episodes of reduced oxygenation in term infants in car seats.

METHODS

Healthy full-term babies were randomized to be studied during sleep while restrained in an infant car safety seat either with or without the insert, with continuous polysomnographic recordings with sleep video.

RESULTS

Seventy-eight infants (39 in each group) had polysomnogram recordings at a mean of 8 days of age. Both groups showed a small fall in mean hemoglobin oxygen saturation (SpO2) over the first hour of sleep. There was no difference between insert and no insert in the rate of moderate desaturations (a fall in SpO2 ≥ 4% lasting for ≥ 10 seconds, mean ± SEM, 17.0 ± 1.5 vs 17.2 ± 1.5/hour), or mean SpO2 during sleep. The insert was associated with a significant reduction in the rate of obstructive apnea (0.3 ± 0.1 vs 0.9 ± 1.5/hour, P < .03), the severity of desaturation events (minimum SpO2 82% ± 1% vs 74% ± 2%, P < .001), and time with SpO2 <85% (0.6% ± 0.3% vs 1.8% ± 1.4%, P = .03).

CONCLUSIONS

In full-term newborn infants, a car seat insert that helps the head to lie in a neutral position was associated with reduced severity of desaturation events but not the overall rate of moderate desaturations.

An evaluation of the Pi analysis in the assessment of anteroposterior jaw relationship

OBJECTIVE

This study has investigated two new cephalometric variables, the Pi angle and Pi linear in the evaluation of anteroposterior skeletal discrepancy.

DESIGN

Retrospective cross-sectional study.

SETTING

Manipal College of Dental Sciences, Manipal, India

SUBJECTS AND METHOD

A sample of 155 subjects (mean age 19·7 years) were subdivided into skeletal class I, II and III groups based upon ANB angle. Descriptive data were calculated for each variable and group. Receiver operating characteristics curves were used to examine sensitivity and specificity of the Pi angle in the discrimination between different skeletal groups. Correlation coefficients were obtained for each of the parameters to compare their relationship with other parameters in the class I group. Coefficient of determination, regression coefficient, regression equation and standard error of estimate were also calculated from the parameters showing significant correlation with the Pi angle.

RESULTS

Mean values for the Pi angle in skeletal class I, II and III subjects were 3·40 (±2·04), 8·94 (±3·16) and -3·57 (±1·61) degrees, respectively. For the Pi linear they were 3·40 (±2·20), 8·90 (±3·56) and -3·30 (±2·30) mm for class I, II and III subjects, respectively. Receiver operating characteristic curves showed that a Pi angle greater than 5 degrees had 89% sensitivity and 82% specificity for discriminating a skeletal class II group from class I. A Pi angle of less than 1·3 degrees had 100% sensitivity and 84% specificity in discriminating skeletal class III groups from class I. The overall accuracy for discriminating class II groups from class I was 85% and for class III from class I, 90%. Thus, a cut-off point between class I and II groups could be considered a Pi angle of approximately 5 degrees and between class I and class III, approximately 1·3 degrees. There were no statistically significant correlations found between Pi angle and ANB (0·07), Beta angle (-0·04) and WITS analysis (0·19). The highest level of correlation was obtained for the Pi angle and Pi linear (0·96).

CONCLUSION

The anglar and linear components of the Pi analysis are a suitable method for assessing anteroposterior jaw discrepancy in daily clinical practice.

A cephalometric investigation of horizontal lip position in adult Nigerians

OBJECTIVES

The aims of this study were to (1) identify soft tissue cephalometric norms for horizontal lip position in an adult Nigerian population; (2) compare values for Nigerian males and females; and (3) compare Nigerian norms with established norms for Caucasians and other populations.

DESIGN

A cross-sectional descriptive study.

SETTING

Lagos University Teaching Hospital Dental Clinic, Idi-araba, Lagos, Nigeria.

PARTICIPANTS

One hundred students (44 males and 56 females) of the College of Medicine, University of Lagos, aged 18-25 years, of Nigerian ancestry, with a normal class I occlusion and no facial asymmetry.

METHODOLOGY

Lateral cephalometric radiographs of the subjects were taken in natural head position. Radiographs were manually traced and 11 soft tissue cephalometric parameters measured. These were derived from the Steiner, Ricketts, Burstone, Merrifield and Holdaway soft tissue analyses. Male and female values were compared using Student's t-test with a level of significance at P<0·05.

RESULTS

Statistically significant differences were observed between Nigerian males and females in eight of the variables studied, with males having more protrusive upper and lower lips than the females. Variables, which did not vary by sex, were soft tissue facial angle, nose prominence and soft tissue chin thickness. In addition, Nigerian norms were higher than norms reported by Steiner, Ricketts, Burstone and Holdaway for Caucasian populations, while the Z-angle was lower than the norm established by Merrifield.

CONCLUSIONS

Gender-specific soft tissue norms for horizontal lip position should be used for orthodontic treatment planning in Nigerian subjects. Nigerians have more protrusive upper and lower lips compared to Caucasians.

A specialized motion capture system for real-time analysis of mandibular movements using infrared cameras

BACKGROUND

In the last years, several methods and devices have been proposed to record the human mandibular movements, since they provide quantitative parameters that support the diagnosis and treatment of temporomandibular disorders. The techniques currently employed suffer from a number of drawbacks including high price, unnatural to use, lack of support for real-time analysis and mandibular movements recording as a pure rotation. In this paper, we propose a specialized optical motion capture system, which causes a minimum obstruction and can support 3D mandibular movement analysis in real-time.

METHODS

We used three infrared cameras together with nine reflective markers that were placed at key points of the face. Some classical techniques are suggested to conduct the camera calibration and three-dimensional reconstruction and we propose some specialized algorithms to automatically recognize our set of markers and track them along a motion capture session.

RESULTS

To test the system, we developed a prototype software and performed a clinical experiment in a group of 22 subjects. They were instructed to execute several movements for the functional evaluation of the mandible while the system was employed to record them. The acquired parameters and the reconstructed trajectories were used to confirm the typical function of temporomandibular joint in some subjects and to highlight its abnormal behavior in others.

CONCLUSIONS

The proposed system is an alternative to the existing optical, mechanical, electromagnetic and ultrasonic-based methods, and intends to address some drawbacks of currently available solutions. Its main goal is to assist specialists in diagnostic and treatment of temporomandibular disorders, since simple visual inspection may not be sufficient for a precise assessment of temporomandibular joint and associated muscles.

Reproducibility of Frankfort horizontal plane on 3D multi-planar reconstructed MR images

Objective

The purpose of this study was to determine the accuracy and reliability of Frankfort horizontal plane identification using displays of multi-planar reconstructed MRI images, and propose it as a sufficiently stable and standardized reference plane for craniofacial structures.

Materials and Methods

MRI images of 43 subjects were obtained from the longitudinal population based cohort study SHIP-2 using a T1-weighted 3D sequence. Five examiners independently identified the three landmarks that form FH plane. Intra-examiner reproducibility and inter-examiner reliability, correlation coefficients (ICC), coefficient of variability and Bland-Altman plots were obtained for all landmarks coordinates to assess reproducibility. Intra-examiner reproducibility and inter-examiner reliability in terms of location and plane angulation were also assessed.

Results

Intra- and inter-examiner reliabilities for X, Y and Z coordinates of all three landmarks were excellent with ICC values ranging from 0.914 to 0.998. Differences among examiners were more in X and Z than in Y dimensions. The Bland–Altman analysis demonstrated excellent intra- as well as inter-examiner agreement between examiners in all coordinates for all landmarks. Intra-examiner reproducibility and inter-examiner reliability of the three landmarks in terms of distance showed mean differences between 1.3 to 2.9 mm, Mean differences in plane angulation were between 1.0° to 1.5° among examiners.

Conclusion

This study revealed excellent intra-examiner reproducibility and inter-examiner reliability of Frankfort Horizontal plane through 3D landmark identification in MRI. Sufficiently stable landmark-based reference plane could be used for different treatments and studies.

[Search of a cephalometric reference line]

The variability of cephalometric reference lines is examined in this article with regard to typology, natural orientation of the head, orientation by the vestibular system, and anatomy. It appears that these lines have orientations that vary with individual subjects, that is, a line is not the same in a specific person as it is in a theoretical model that is based on average values. It follows from this that the deviation observed between a patient's measurement and the average could just as well reflect variations in the reference lines as it does of those of the structures being studied. Such a measurement cannot, accordingly, serve as the basis for a morphological diagnosis. To deal with this problem, we propose another cephalometric reference system that presents, for orthognathic diagnosis, many advantages over the traditional system but, itself, remains imperfect.