Midface Length Research Articles

Treatment with an inhibitor of matrix metalloproteinase 9 or cathepsin K lengthens embryonic lower jaw bone.

Skeletal malocclusions are common, and severe malocclusions are treated by invasive surgeries. Recently, jaw bone length has been shown to be developmentally controlled by osteoclasts. Our objective was to determine the effect of inhibiting osteoclast-secreted proteolytic enzymes on lower jaw bone length of avian embryos by pharmacologically inhibiting matrix metalloproteinase-9 (MMP9) or cathepsin K (CTSK). Quail (Coturnix coturnix japonica) embryos were given a single dose of an inhibitor of MMP9 (iMMP9), an inhibitor CTSK (iCTSK), or vehicle at a developmental stage when bone deposition is beginning to occur. At a developmental stage when the viscerocranium is largely calcified, the heads were scanned via micro-computed tomography and reproducible landmarks were placed on 3D-reconstructed skulls; the landmark coordinates were used to quantify facial bone dimensions. Approximately half of the quail given either iMMP9 or iCTSK demonstrated an overt lower jaw phenotype, characterized by longer lower jaw bones and a greater lower to upper jaw ratio than control embryos. Additionally, iMMP9-treated embryos exhibited a significant change in midface length and iCTSK-treated embryos had significant change in nasal bone length. MMP9 and CTSK play a role in osteoclast-mediated determination of lower jaw bone length. Pharmacological inhibition of MMP9 or CTSK may be a promising therapeutic alternative to surgery for treating skeletal jaw malocclusions, but more preclinical research is needed prior to clinical translation.

Aesthetic Crown Lengthening Using Chu Proportion Gauges: A Case Report

Background: A harmonious smile is considered a symbol of beauty in modern society. Generally, a smileis considered pleasant when it normally exposes all of the maxillary teeth, as well as around 1 mmof facial gingiva. The gingival exposure of up to 2-3 mm is normally acceptable. The rehabilitation performed for the abnormalities in symmetry and contour of the gingiva in this region can be challenging. Crown-lengthening surgery is used in combination with perio-aesthetic procedures to repair gingival asymmetries and realign the dentogingival complex. The Chu’s aesthetic gauges were designed to diagnose and treat aesthetic tooth discrepancies and abnormalities in a predictable manner.
 Objective: To attain optimal crown lengthening using Chu’s aesthetic gauges.
 Case Report: A 21-year-old female patient presented to the Department of Periodontology, with a request for “better-looking teeth”. Extraoral examination revealed no significant findings. No mobility and adequate levels of keratinized attached gingiva on intraoral examination. The case was diagnosed as a gummy smile, that could be repaired with crown lengthening. During the surgical crown-lengthening, Chu’s aesthetic gauges were used to measure the midfacial length of the biologic crown at the same time. These gauges are unique technique that is innovative and a novel method to get adequate crown proportions. Results: Evaluation after two weeks after the surgery showed a better-looking smile line and no erythema.
 Conclusion: A successful crown-lengthening procedure was performed using Chu’s aesthetic measurement, including optimal dimension of clinical crowns and symmetrical gingival contour.
 Keywords: crown lengthening, aesthetic procedure, Chu’s aesthetic gauges, case report

Simplifying Diagnosis of Fetal Alcohol Syndrome Using Machine Learning Methods.

IntroductionThe fetal alcohol spectrum disorder (FASD) is a complex and heterogeneous disorder, caused by gestational exposure to alcohol. Patients with fetal alcohol syndrome (FAS—most severe form of FASD) show abnormal facial features. The aim of our study was to use 3D- metric facial data of patients with FAS and identify machine learning methods, which could improve and objectify the diagnostic process.Material and MethodsFacial 3D scans of 30 children with FAS and 30 controls were analyzed. Skeletal, facial, dental and orthodontic parameters as collected in previous studies were used to evaluate their value for machine learning based diagnosis. Three machine learning methods, decision trees, support vector machine and k-nearest neighbors were tested with respect to their accuracy and clinical practicability.ResultsAll three of the above machine learning methods showed a high accuracy of 89.5%. The three predictors with the highest scores were: Midfacial length, palpebral fissure length of the right eye and nose breadth at sulcus nasi.ConclusionsWith the parameters right palpebral fissure length, midfacial length and nose breadth at sulcus nasi, machine learning was an efficient method for the objective and reliable detection of patients with FAS within our patient group. Of the three tested methods, decision trees would be the most helpful and easiest to apply method for everyday clinical and private practice.

Twelve-Year Experience With Nasofrontal Angle (Radix) Augmentation in Rhinoplasty.

The nasofrontal angle (radix) has a great impact on the rhinoplasty outcome. Minimal alterations in this area can give an unusual nasal appearance and midfacial length. Different management approaches have been described with regard to radix augmentation. This study aimed to describe the techniques of rhinoplasty, different materials used in the procedure, and results of at least 1 year of follow-up in our 12-year experience in this field. The authors retrospectively reviewed the data of patients who underwent rhino-plasty/septorhinoplasty with radix augmentation performed by 1 of the authors (a senior surgeon at our institution) using different graft materials, between January 2007 and December 2019. Patients younger than 18 years or who were followed up for less than 1 year were excluded from the study. In total, 387 patients (235 [60.7%] female; age range, 19–39 years) were included. Primary procedures were performed in 311 patients (80.5%), and revision procedures were performed in 76 patients (19.6%). Most patients (97%) were satisfied with the aesthetic result. There was no incidence of infection, displacement, or extrusion of the graft. The only complications observed were irregularities; 3% required revision surgery. It is important to consider the nasal radix when pursuing a balanced profile in rhinoplasty. Many graft materials can be used safely and can achieve good aesthetic outcomes. Proper anatomical analysis and patient selection are essential for successful graft placement.

Üst Gömülü Kanin Dişlerin Maksiller Kaide ile İlişkisinin Değerlendirilmesi

Objective: The aim of this study was to evaluate the relationship between impacted maxillary canine teeth and maxillary base length.Material-Method: 142 patients (67 males, 75 females; a mean age of 16.34±1.07 years) who were admitted to the Department of Orthodontics of İstanbul Aydın University - Faculty of Dentistry for treatment were included in our study. In the retrospective study, the positions of maxillary canine teeth and their relationship with maxillary base length were examined in detail in cephalometric and panoramic radiographs. Results with p <0.05 were found to be statistically significant.Results: There was no statistically significant correlation was found between gender and canine impaction. Unilaterally impacted upper canines were found to be higher between genders. Palatal plane value of the unilaterally impacted canine group was found to be statistically greater. Significant difference was found between palatal plane variable and impacted canine. No significant difference was found between age and effective midfacial length variables based on canine. Examination of the correlation between effective midfacial length and palatal plane variables revealed a strong positive correlation, which was statistically significant. There was no significant difference between age, effective midfacial length and palatal plane variables in terms of gender.Conclusion: This study is the first to specifically address the relationship of impacted canines with the palatal plane. Therefore, the position of the canines has a major place in the evaluation of their relationship with the adjacent anatomical structures and teeth, especially during treatment planning.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy.

The aim of this study was to evaluate three-dimensional (3D) effects of Twin-block functional appliance (TB) on the pharyngeal airway by using cone beam computed tomography (CBCT). A total of 30 patients (14 females, 16 males; mean age 12.50 ± 1.23 and 12.83 ± 1.17 years, respectively) with skeletal Class II malocclusion were included in this study and were treated with TB. On the pretreatment (T1) and posttreatment (T2) CBCT scans, volumetric changes in the pharyngeal airway; SNA, SNB, and ANB angles; and bilateral effective mandibular (Co-Gn) and midfacial length (Co-A) were also evaluated. The statistical differences were accessed by Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to analyze the scores of male and female subjects. In this study, an increase was observed in SNB and Co-Gn (p < 0.01) while a decrease in ANB and SNA (p < 0.01 and p < 0.05, respectively) was found. However, increase in midfacial length was not statistically significant (p > 0.05). In the evaluation of volumetric pharyngeal airway changes, statistically significant increases (p < 0.01) in the upper and lower division and total airway volume were determined. Gender differences were insignificant for all measurements (p > 0.05). Volumetric changes in the pharyngeal airway after functional therapy can be successfully evaluated by CBCT images. The anterior repositioning of the mandible by TB increases the mandibular length and pharyngeal airway volume in patients with retrognathic mandible.

Effect of positional errors on the accuracy of cervical vertebrae maturation assessment using CBCT and lateral cephalograms

BackgroundThe objective of this study was to evaluate the effects of single plane and multiplane rotational errors in yaw, pitch, and roll of the head while recording the lateral cephalogram on CVM (cervical vertebrae maturity) assessment. MethodsA total of 40 cone-beam computed tomography (CBCT) scans and 360 lateral cephalograms were analyzed for patients with different rotations: Controls (no rotation), Y5 (yaw 5° rotation), Y10 (yaw 10° rotation), R5 (roll 5° rotation), R10 (Roll 10° rotation), P5 (pitch 5° rotation), P10 (pitch 10° rotation), YRP5 (yaw, roll, and pitch 5° rotation), and YRP10 (yaw, roll, and pitch 10° rotation). The C2, C3, and C4 concavity and their base-anterior ratio and posterior-anterior ratio were measured. In addition, maxillomandibular linear parameters, such as effective mandibular length and height, mandibular body length, effective midface length, and maxillomandibular differential, were also evaluated. ResultsY5, Y10, R5, and R10 led to overestimation of CVM in comparison with controls. Multiplane rotations (YRP5 and YRP10) led to more inaccuracies in CVM measurements than single plane rotations; 10° of rotation led to more inaccuracies than 5° of rotation while recording the lateral cephalogram, irrespective of the plane. Yaw rotational errors led to an underestimation of maxillomandibular linear measurements, whereas roll rotational errors led to an overestimation of the measurements; however, there were wide individual variations in the measurements between the different rotations and controls. ConclusionsRotational errors lead to overestimation of CVM assessment. Multiplane rotations cause higher inaccuracies than single plane rotations. Increased degree of rotations while capturing the lateral cephalograms lead to more inaccuracies in CVM assessment.

Regulatory Dynamics of Midfacial Growth in Evolution and Disease

Craniofacial morphogenesis demands coordinated outgrowth of spatially‐separated facial prominences. Underscoring this complex choreography, 1/3 of all human birth defects affect craniofacial development. Both orofacial clefting and malocclusions are common birth abnormalities that affect the midface. During midfacial development, regulatory genes control the dynamics of transcriptional activity, tissue patterning, and intercellular signaling to modulate the timing of morphogenetic and growth processes. Variation in these dynamics underlies both evolutionary divergence in midfacial outgrowth and the etiology of craniofacial birth defects. In non‐avians, the main variable driving species‐specific midfacial length is the maxilla of the upper jaw, while in avians it is the premaxilla. Also, avians have cleft palate in physiological conditions. Despite the availability of datasets of regulatory elements from craniofacial tissues and cranial neural crest cells, the majority of regulatory networks that control embryonic midfacial outgrowth are unknown with respect to their in vivo spatiotemporal context‐dependence. We are establishing regulatory landscapes that control different morphogenetic and outgrowth characteristics of midfacial elements at the organismal level in chick, mouse, and pig embryos, species characterized by remarkably different midfacial lengths. To this end, we are combining 3D gene expression profiles obtained via High Resolution Episcopic Microscopy (HREM) of embryos processed by whole mount in situ hybridization as well as genome‐wide transcriptional regulatory activity and epigenetic regulation assessed by RNA Seq, ATAC‐Seq, and chromatin mark ChIP‐Seq of embryonic midfacial anlagen. By this approach, we have identified candidate genes that regulate maxillary‐specific morphogenetic programs in avians versus mammals. One of these genes, which encodes a transcription factor (TF) bearing zinc finger motifs and a homeobox motif, is expressed meristically along the AP palatal shelf of mouse embryos at E11.5–14.5, but is not expressed in the palatal shelves of avian embryos at the corresponding developmental stages. Mice we generated with CRISPR/Cas‐mediated loss‐of‐function of this TF show cleft palate and stunted snout. Strikingly, children with a deletion of this TF exhibit high‐arched palate and cleft palate. These findings establish mechanisms underlying tolerance to morphological variation that separate normal development and evolution of craniofacial features from malformations associated with birth defects.Support or Funding InformationUCSF Recruitment Funds

The Sphenoidal Synchondroses: Implications for the Midfacial Growth of Anthropoid Primates

The basicranium of anthropoid primates is more flexed than in lemurs and lorises (strepsirrhines), which has implications for orientation of facial growth. Differential growth among cranial synchondroses is one suggested mechanism for variation in basicranial development. In this study, we measured length of bony elements of the cranial base using Amira software in a cross‐sectional age sample (late prenatal to juvenile), which included three monkey species and four species of lemurs and bushbabies (n = 59). In addition, we made preliminary measurements of the anteroposterior length of the spheno‐occipital synchondrosis (SOS), intrasphenoidal synchondrosis (ISS), and prespheno‐septal synchondrosis (PSept) using newborn samples. In order to assess differences in growth potential among sync hondroses, the diameter of the proliferating (PZ) or hypertrophic (HZ) zones were also measured. Our other work has indicated that measurements of ossified elements of the cranial base reveal disproportionately more growth of presphenoid (PS) relatively to basisphenoid (BS) in monkeys. But in strepsirrhines, these bones scale similarly to one another when plotted against increasing cranial or midfacial length. When expressed as a ratio of the length of the PZ or HZ to total anteroposterior diameter of the synchondrosis, growth is relatively similar in ISS and SOS among all species studied. However, in anthropoids the length of the PZ in PSept is notably (more than two‐fold) greater than in any other synchondrosis. In strepsirrhines, length of the PZ in PSept is relatively similar to the same zone of other synchondroses. This suggests that the rapid increase in length of the presphenoid in anthropoids is mostly occurring anteriorly, at the midfacial interface. These results, taken at face value, might suggest that anthropoids have a greater magnitude of growth in the septal cartilage compared to strepsirrhines. However, our previous work established that growth at PSept in more multidirectional (radial) than in most other mammals. Instead, our findings emphasize different patterns of sphenoid growth among primates, and offer a tissue‐level explanation for the relatively large PS segment in anthropoid primates. In addition, these findings indicate suggest that growth of the sphenoid is more highly integrated with PS than BS and more interdependent with facial growth in monkeys than in strepsirrhine primates.Support or Funding InformationNSF grant # BCS‐1830894, BCS‐1830919, BCS‐0959438

A multilevel analysis of craniofacial growth in subjects with untreated Class III malocclusion.

To analyse the craniofacial growth of a long-term semi-longitudinal sample of Caucasian subjects with untreated Class III malocclusion. A total of 144 Caucasian subjects (of North American and Italian origin) with untreated Class III malocclusion. Subjects aged 2years and 9months up to 21years and 7months were selected. A multilevel model was used to calculate growth curves for ten variables for both each individual subject and for the whole sample. There was a statistically significant increase for total mandibular length (Co-Gn. T2-T1=8.4mm), midfacial length (Co-A. T2-T1=3.4 mm) and lower anterior facial height (ANS-Me. T2-T1=3.8 mm). The multilevel analysis showed two points of acceleration of growth (about 3-5years of age and 11-15years of age) for seven out of ten variables. For Co-Gn and Co-A variables, males presented points of maximum growth delayed by 1year in comparison with females, with a greater duration (1year longer) and a greater total growth of about 5mm. Active mandibular growth continued for a long time after the pubertal spurt: increases in mandibular length ended at about 17years of age in females and at 21years and 7months in males. Untreated Class III malocclusion showed a specific growth curve, especially for the mandible, whose excesses added up over time. In males, the amounts of mandibular and midfacial growth during the whole observation time were greater and lasted longer than in females.

McNamara Cephalometric Analysis oF Newars of Kathmandu

Introduction: Standardized cephalogram is used for the orthodontic diagnosis and treatment planning and the measured values of the craniofacial structures are compared with the peer group having similar age, gender and ethnicity. However, this standardized comparison has not been possible so far for Newar ethnic group.Objective: To determine cephalometric norms of Newar adults of Kathmandu using McNamara analysis and to assess gender difference within the group. Materials &amp; Method: Newar Indo-Aryan descendents aged 18-27 years were screened based on inclusion criteria. Lateral cephalometric radiographs of 62 untreated Newar adults (20 males and 42 females) were used. Manual tracing of the lateral cephalograms were performed and descriptive statistics were obtained. Comparative test was conducted within Newars to evaluate gender diversity at the significance level p≤0.05. Result: Craniofacial structures of male and female Newars were significantly different. Parameters showing these differences were Effective Mid Face Length, Effective Mandibular Length, Lower Anterior Facial Height.Conclusion: Standardized comparison with the peer group separately for male and female should be done when analysing cephalometry for any ethnic group.

Treatment effects of mandibular anterior position training versus a fixed Class II corrector in growing patients with skeletal Class II malocclusion

PurposeTo compare treatment effects of Class II elastics and anterior mandibular position training against fixed Class II corrector (PowerScope™) during the correction of skeletal Class II malocclusion with fixed appliance in growing patients. Materials and methodsThirty-six growing patients with skeletal Class II malocclusion with a retruded pogonion position were randomly allocated to the Class II elastics or PowerScope™ groups. Preadjusted edgewise fixed appliances were used in both treatment groups. Skeletal, dental and profile changes were compared using lateral cephalograms taken before (T0), after initial alignment (T1) and after Class I obtained (T2) for 16/18 patients in the Class II elastics group and 15/18 patients in the PowerScope™ group. ResultsThe duration of treatment was significantly longer for the Class II elastics group than PowerScope™ group. In terms of skeletal changes, Class II elastics increased mandibular length, midfacial length and mandibular plane angle significantly more than the PowerScope™. In terms of dental changes, Class II elastics increased dental height significantly more than the PowerScope™. ConclusionsBoth treatment modalities reduced severity of Class II malocclusion and decreased profile convexity. Class II elastics with anterior mandibular position training increased mandibular length more but required longer treatment duration. The PowerScope™ had a greater effect on maxillary dento-alveolar restriction. (ClinicalTrials.in.th: TCTR 20180220003).

MCNAMARA’S CEPHALOMETRIC NORMS OF EGYPTIAN CHILDREN

Objective: To establish McNamara Cephalometric Analysis normative data for Egyptian children. Materials and Methods: Twenty boys and forty girls (mean age 9.37, SD 1.60) of Egyptian ethnicity were selected based on the following criteria: Class I molar relationship, lack of crossbite or scissor-bite, adequate amount of space in dental arches, no visible asymmetry, and good facial proportions. Eleven selected variables from McNamara’s cephalometric method were digitally traced and analyzed on the lateral cephalograms of each subject. Results: McNamara’s skeletal and dental variables were assessed and statistically significant inter-gender differences were noted in both effective midface length (condylion to point A) and effective mandibular length (condylion to gnathion). Conclusions: Young Egyptian boys had a lengthier midface and mandible than girls. The Upper incisors to point A vertical and lower incisor to A-PO line were slightly more pronounced in girls.

Abstract: CT Analysis of Micrognathia: Do Cephalometrics Predict Management Course?

INTRODUCTION: Mandibular micrognathia is the primary defining characteristic of Pierre Robin Sequence (PRS) that sets off a physiologic cascade with varying severity of airway obstruction.1 The diagnosis of micrognathia is predominantly clinical, though with the advent of three-dimensional computed tomography (3D-CT), the development of objective and accurate measurements of skeletal morphology could be a useful clinical adjunct for management.2 The aim of this study is to investigate the efficacy of using cephalometric analysis to guide clinical management: non-operative treatment, mandibular distraction, tracheostomy. METHODS: Records were retrospectively reviewed from 2004–2016 (IRB#2011-0247). Infants less than one year of age with PRS, evaluated for surgical management of micrognathia with a CT scan were included. 3D-CT analysis of total mandibular length (Co-Gn) and total midface length (Co-A) was performed in addition to traditional cephalometric analysis – Co-Gn, Co-A, SNA, SNB, ANB – in reformatted sagittal CT scans. Clinical data collected included age at CT scan, sex, and associated syndromic status. Chi-squared and Kruskal-Wallis tests were used to compare values among patients that were managed non-operatively, with mandibular distraction osteogenesis (MDO), and tracheostomy at any point, with Mann-Whitney U test reserved for comparing two groups. RESULTS: 147 patients met inclusion; 33 non-operative, 73 MDO, 41 tracheostomy. CT scans were performed at an older age in the tracheostomy group compared to the non-operative and MDO groups (96.3, 58.3, 39.4 days, respectively; p=0.02). Likewise, the tracheostomy group had a greater proportion of syndromic patients compared to non-operative and MDO groups (76%, 36%, 40%, respectively; p=0.0003). Traditional cephalometric measures demonstrated no differences among the groups: Co-Gn (non-operative: 43.0mm, MDO: 41.2mm, tracheostomy: 41.1mm; p=0.17), Co-A (41.7, 40.7, 41.5mm, respectively; p=0.28), ANB (18.1°, 19.2°, 20.3°, respectively; p=0.37), SNA (84.3°, 83.0°, 84.0°, respectively; p=0.46), and SNB (66.1°, 63.8°, 63.6°, respectively; p=0.14). 3D-CT analysis of total mandibular length (46.3, 46.2, 45.2mm, respectively; p=0.48) and total midface length (49.3, 48.5, 48.5mm, respectively; p=0.37) did not differ among groups. CONCLUSION: Cephalometric measurements from computed tomographic scans did not differ among patients that were managed non-operatively, underwent mandibular distraction, or tracheostomy. These results illustrate the limitation of solely using skeletal data as a means to predict the need for surgical intervention for airway compromise. Reference Citations: 1. Pruzansky S, Richmond JB. Growth of Mandible in Infants with Micrognathia Clinical Implications. Archives of Pediatrics & Adolescent Medicine. 1954;88(1):29. doi:10.1001/archpedi.1954.02050100031005. 2. Breugem CC, Evans KN, Poets CF, et al. Best Practices for the Diagnosis and Evaluation of Infants With Robin Sequence. JAMA Pediatrics. 2016;170(9):894. doi:10.1001/jamapediatrics.2016.0796.

Cone beam computed tomography-based cephalometric norms for Brazilian adults

This study established cone beam computed tomography (CBCT)-based cephalometric norms for Brazilian adults, including the assessment of sexual dimorphism. An observer performed McNamara’s cephalometric analysis twice on 60 CBCT datasets acquired from patients with a normal dental occlusion, divided equally into two groups by sex. Welch’s t-test was applied to assess differences between the sexes in hard tissue cephalometric measurements, and Dahlberg’s formula was used to calculate measurement error introduced by the observer. The cephalometric measurements of effective mandibular length, effective midfacial length, maxillomandibular differential, and lower anterior facial height presented sexual dimorphism. Linear measurements had error ≤0.78mm, and angular measurements had error ≤1.24°. The results show that (1) the CBCT-based cephalometric norms established in this study are reliable for use by researchers and clinicians, and (2) Brazilian adult males and females have similar craniofacial morphology, with males possessing larger jaws than females.

Lateral Cephalometric Linear Measurement Standards of Mongolian Children with Normal Occlusion from 6-7 Years of Age

Objectives: The aim of this study was to analyze craniofacial linear dimensions in subjects with normal occlusions to establish age and gender-specific lateral cephalometric linear measurement norms for Mongolian children. Methods: 161 six year old children and 122 seven year old children were recruited for this study. Digital cephalograms of 75 six year old children (34 male and 41female), 49 seven year old children (22 male and 27 female) were selected to establish lateral cephalometric linear measurement norms. Anatomic landmarks were identified directly on the digital images. The means and standard deviations of linear measurements were calculated using 18 variables. Student’s t-test was employed to test for gender differences in each age. Results: Anterior cranial base length and midfacial length were significantly larger in six year old male subjects. Mo-Ms and A-Ptm were significantly larger in seven year old male subjects. Conclusion: Our results showed that linear craniofacial dimension of the hard tissue was gender-dependent. Therefore, gender-specific differences of craniofacial distances should be taken into account during diagnosis and treatment planning. The results from this study can be used as reference values for 6-7 years old children of Mongolia.

Use of repeat anterior maxillary distraction to correct residual midface hypoplasia in cleft patients.

ObjectivesThe study was designed to evaluate the efficacy of performing a second, repeat anterior maxillary distraction (AMD) to treat residual cleft maxillary hypoplasia.Materials and MethodsFive patients between the ages of 12 to 15 years with a history of AMD and with residual cleft maxillary hypoplasia were included in the study. Inclusion was irrespective of gender, type of cleft lip and palate, and the amount of advancement needed. Repeat AMD was executed in these patients 4 to 5 years after the primary AMD procedure to correct the cleft maxillary hypoplasia that had developed since the initial procedure. Orthopantomogram (OPG) and lateral cephalograms were taken for evaluation preoperatively, immediately after distraction, after consolidation, and one year postoperatively. The data obtained was tabulated and a Mann Whitney U-test was used for statistical comparisons.ResultsAt the time of presentation, a residual maxillary hypoplasia was observed with a well maintained distraction gap on the OPG which ruled out the occurrence of a relapse. Favorable movement of the segments without any resistance was seen in all patients. Mean maxillary advancement of 10.56 mm was achieved at repeat AMD. Statistically significant increases in midfacial length, SNA angle, and nasion perpendicular to point A distance was achieved (P=0.012, P=0.011, and P=0.012, respectively). Good profile was achieved for all patients. Minimal transient complications, for example anterior open bite and bleeding episodes, were managed.ConclusionAddressing the problem of cleft maxillary hypoplasia at an early age (12–15 years) is beneficial for the child. Residual hypoplasia may develop in some patients, which may require additional corrective procedures. The results of our study show that AMD can be repeated when residual deformity develops with the previous procedure having no negative impact on the results of the repeat procedure.

Long-term orthognathic surgical outcomes in Treacher Collins patients

Treacher Collins syndrome is a rare disorder characterized by several orofacial findings including malar deficiency and hypoplastic mandibles. These patients often require a combined orthodontic-orthognathic approach to correct their malocclusion. This is most often characterized by a short posterior vertical height and an anterior open bite. Orthognathic correction often requires Le Fort I and bilateral sagittal split osteotomies. No long-term stability results have been reported after bimaxillary surgery in Treacher Collins patients. A retrospective review of all Treacher Collins patients evaluated for orthognathic surgery by a single surgeon from 1993 to 2007 was performed. Patients were divided into groups who required surgery and those who did not. Part I analyzed the cephalometric differences between the surgical (S) and nonsurgical (NS) groups. Part II of the study assessed the preorthodontic treatment (T1), preoperative (T2), immediate postoperative (T3), and 1-year postoperative (T4) cephalometric measurement variables to determine the net surgical movement (T3 - T2) and relapse (T4 - T3). Twenty-two patients met the inclusion criteria, of which 11 had occlusal relationships requiring orthognathic surgery. Nine out of 11 chose to have surgery. At baseline, surgical patients exhibited a statistically significant retruded maxilla as measured by SNA and midface length compared to the NS group. In addition, the S group also had an increased gonial angle. There were significant movements in all maxillary and mandibular measurements. There was a significant relapse in the palatal plane angle when the maxilla was anteriorly impacted, with a 2.8-mm average relapse of the advancement. Relapse of the counterrotation movement of the mandible was identified, but this was not significant. Relapse did not affect the final occlusal result, which may have been compensated with postsurgical orthodontic treatment. Bimaxillary orthognathic surgery in the Treacher Collins patients may be performed safely with long-term dental and skeletal stability.

The usefulness of cephalometric measurement as a diagnostic tool for obstructive sleep apnea syndrome: a retrospective study.

Obstructive sleep apnea syndrome (OSAS) is a disorder characterized by apnea and hypopnea maintained for over 10seconds and occurring at least 5 times per hour, with at least 30 episodes during 7hours of nocturnal sleep. The most important pathophysiology in OSAS is the obstruction of the upper airway during sleep. The aim of this study was to identify the correlations between lateral cephalometric parameters, which seemed to be related to OSAS severities, and polysomnography (PSG) indices and to thus determine the cephalometric parameters reflecting OSAS severity. A total of 140 participants (122 males, 18 females) were evaluated by lateral cephalography and PSG. A total of 29 measurements (24 distances and 5 angles) were made on lateral cephalography. Cephalometric and PSG parameters were evaluated statistically to select and validate the cephalometric parameters reflecting OSAS severity. OSAS has a significant relationship with the anatomic deformities of craniofacial and soft tissues. Lateral cephalometry revealed that patients with OSAS have a significant vertical airway length, a regrognathic mandible, a thick uvula, a large tongue, and a long mid-face length. The position of the hyoid bone had a tendency to displace inferiorly and/or posteriorly. Using the discriminant variable combination, including tongue base-posterior nasal spine (T1-PNS), sella-nasion-B point angle (SNB), maximum uvula thickness (Max U), tongue base-tongue tip (T1-TT), and nasion-anterior nasal spine (N-ANS), 102 of 140 (72.9%) patients were correctly assigned to the normal-to-mild and moderate-to-severe apnea-hypopnea index (AHI) groups. Lateral cephalometric radiography may be an accessible and suitable tool for evaluation of craniofacial and soft tissue deformities in their correlations with OSAS severity. Further research on the cephalometric parameters reflecting OSAS severity is needed.

Condylar response to functional therapy with Twin-Block as shown by cone-beam computed tomography

To evaluate the condylar changes through cone-beam computed tomography (CBCT) images in patients treated with Twin-Block functional appliance. In this retrospective study, CBCT images of 30 patients who were treated with the Twin-Block appliance were used. Mandible was segmented and pretreatment and posttreatment (T0 and T1) condylar volume was compared. The angle between sella-nasion-Point A (SNA), angle between sella-nasion-Point B (SNB), angle between Point A-nasion-Point B (ANB), midfacial length (Co-A), mandibular length (Co-Gn), and the distances from right condylion to left condylion (CoR-CoL) were also measured on three-dimensional images. Differences were analyzed with Wilcoxon signed rank tests, and Mann-Whitney U-tests were used to compare the scores of male and female participants. Significance was set at P < .05. In this study, a decrease in SNA and ANB (P < .05 and P < .01, respectively) and an increase in SNB (P < .01) were found. Additionally, CoR-CoL, Co-Gn, and condylar volume increased at both the left and right sides (P < .01). However, increase at Co-A was not statistically significant (P > .05). Comparison of differences by sex was not statistically significant for all measurements (P > .05). Twin-Block appliance increases condylar volume, mandibular length, and intercondylar distance by stimulating growth of condyle in an upward and backward direction.