Long-term mandibular growth in patients with airway obstruction treated with mandibular distraction.

Congenital craniofacial malformations play an important role in upper airway obstruction. One of the main causes is mandibular hypoplasia which is present in the pierre robin sequence. Mandibular distraction osteogenesis (MDO) is one of the most commonly used treatments for the resolution of upper airway obstruction in patients that do not respond to a conservative treatment. We performed a long term follow up of syndromic and non-syndromic patients with pierre robin sequence where the lateral xrays were studied before surgery (T1), after MDO (T2) and long-term follow-up (T3, at least 5 years). Possible complications of the surgery were also studied through panoramic x-rays and clinical controls. The results evidenced an increase of mandibular length comparing T1-T2 and a good stability during the long-term follow-up. The Sd patients presented smaller mandible dimensions. We had not found any complications during the follow-up. The scars outcomes are modest, but none of the patients requested a surgical correction. Mandibular distraction osteogenesis is a treatment to be considered in patients with upper airway obstruction that do not respond to conservative treatments. The results of the surgery are stable and the complications in experienced hands are low.

Can Dynamic Magnetic Resonance Images Improve Prenatal Diagnosis of Robin Sequence.

BACKGROUND: Robin sequence (RS) is a triad of micrognathia, glossoptosis, and airway obstruction. Prenatal diagnosis of RS improves delivery planning and postnatal care, but the process for prenatal diagnosis has not been refined. The purpose of this study was to determine if dynamic cine magnetic resonance imaging (MRI) can improve the reliability of prenatal diagnosis for RS compared to current static imaging techniques. MATERIALS AND METHODS: This is a retrospective cross-sectional study including fetuses with prenatal MRIs obtained in a single center from January 2014 to November 2019. Fetuses were included if they: 1) had a prenatal MRI with cine dynamic sequences of adequate quality, 2) were live born, and 3) had postnatal craniofacial evaluation to confirm RS. Patients without postnatal confirmation of their prenatal findings were excluded. The primary predictor variable was imaging type (cine or static MRI). Outcome variables were tongue and airway measurements: 1) tongue height, 2) length and width, 3) tongue shape index, 4) observation of tongue touching the posterior pharyngeal wall, and 5) measurement of oropharyngeal space. All measurements were made independently on the cine images and on static MRI sequences for the same cohort of subjects by a pediatric radiologist. Data were analyzed using paired samples t tests and Fisher exact tests, and significance was set as P < .05. RESULTS: A total of 11 patients with RS were included in the study. The smallest airway space consistently demonstrated complete collapse on the cine series compared to partial collapse on static images (0 mm vs 1.7 ± 1.4 mm, P = .002). No other imaging variable was statistically significantly different between techniques. CONCLUSIONS: Cine imaging sequences on prenatal MRI were superior to static images in discerning complete collapse of the smallest airway space, an important marker of RS. This suggests a possible benefit to adding dynamic MRI evaluation for prenatal diagnosis of this condition.

Safety of Mandibular Osteotomies in Infants with Pierre Robin Sequence: Computer-Aided Modeling to Characterize the Risks of Various Techniques.

BACKGROUND: Mandibular distraction osteogenesis is effective for the correction of severe tongue-based airway obstruction in infants with Pierre Robin sequence. Involved osteotomies may damage developing tooth buds and/or the inferior alveolar nerve. The authors evaluated the theoretical safety of various osteotomy techniques to better define infantile mandibular anatomy using computer-aided modeling. METHODS: Seven mandibular osteotomy techniques (oblique, inverted-L, multiangular, walking stick, high oblique, vertical/high inverted-L, and horizontal) were simulated using computed tomography studies from infants with Pierre Robin sequence and without other associated conditions. Software was used to manually segment the mandibular bone, inferior alveolar nerve, and tooth buds. RESULTS: Sixty-five computed tomography scans were included, yielding 130 hemimandibles. The horizontal osteotomy pattern had significantly lower theoretical risk of tooth bud (p < 0.001) and inferior alveolar nerve involvement (p < 0.001) than all other patterns. Osteotomies with high vertical components (i.e., vertical, walking stick, and multiangular) had lower theoretical tooth bud involvement than the more proximal oblique and inverted-L osteotomies (p < 0.001). Average lingula location was measured at a point 65 percent of the mandibular width from anterior mandibular border and 63 percent of the mandibular height from the inferior mandibular border. CONCLUSIONS: Surgical planning with computed tomography scans can help evaluate an infant's mandibular anatomy to select an osteotomy that reduces morbidity risks. Regardless of technique, tooth buds and the inferior alveolar nerve are often included in osteotomies. The lingula location in this study demonstrates a position more superior and posterior than that previously described. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Evaluating Sensory Nerve Outcomes After Horizontal Osteotomy for Mandibular Distraction in Infant Robin Sequence Patients.

ABSTRACT: There has yet to be a consensus on the appropriate technique for mandibular distraction in the infant Pierre Robin population nor is their sufficient data on sensory nerve outcomes. The purpose of this study is to validate the safety of the horizontal osteotomy by: (1) determining mandibular foramen location in infant Pierre Robin patients relative to the dentoalveolar plane and (2) evaluate long-term function of the inferior alveolar nerve in previously distracted Pierre Robin patients. Preoperative 3D Computed tomography (CT) scans of Pierre Robin patients < 1 year old were reviewed. A line at the level of the mandibular dentoalveolar plane was drawn across the lingual surface of the ramus and the distance to the mandibular foramen was then measured. Semmes-Weinstein monofilaments of the lower lip and chin bilaterally was performed on mandibular distraction patients in clinic. Inclusion criteria was patients >6 years of age having undergone bilateral mandibular distraction at <1 year of age. Fifteen patients' CT studies were examined. The mandibular foramen was consistently below the level of the dentoalveolar plane at an average distance of 4.7 mm. Eight patients were included in the prospective arm. Average age was 12.2. All patients had normal sensation at 2.83 through all areas. The mandibular foramen reliably exists below the dentoalveolar plane. In addition, all patients reviewed postoperatively with >10 years of follow up demonstrated normative sensation. The horizontal corticotomy performed just above the mandibular dentoalveolar plane spares the inferior alveolar nerve in young Pierre Robin patients undergoing distraction.

Accuracy and Reliability of 4D-CT and Flexible Laryngoscopy in Upper Airway Evaluation in Robin Sequence.

OBJECTIVES: To evaluate the performance of 4-dimensional computed tomography (4D-CT) in assessing upper airway obstruction (UAO) in patients with Robin sequence (RS) and compare the accuracy and reliability of 4D-CT and flexible fiber-optic laryngoscopy (FFL). STUDY DESIGN: Prospective survey of retrospective clinical data. SETTING: Single, tertiary care pediatric hospital. METHODS: At initial and 30-day time points, a multidisciplinary group of 11 clinicians who treat RS rated UAO severity in 32 sets of 4D-CT visualizations and FFL videos (dynamic modalities) and static CT images. Raters assessed UAO at the velopharynx and oropharynx (1 = none to 5 = complete) and noted confidence levels of each rating. Intraclass correlation and Krippendorff alpha were used to assess intra- and interrater reliability, respectively. Accuracy was assessed by comparing clinician ratings with quantitative percentage constriction (QPC) ratings, calculated based on 4D-CT airway cross-sectional area. Results were compared using Wilcoxon rank-sum and signed-rank tests. RESULTS: There was similar intrarater agreement (moderate to substantial) with 4D-CT and FFL, and both demonstrated fair interrater agreement. Both modalities underestimated UAO severity, although 4D-CT ratings were significantly more accurate, as determined by QPC similarity, than FFL (-1.06 and -1.46 vs QPC ratings, P = .004). Overall confidence levels were similar for 4D-CT and FFL, but other specialists were significantly less confident in FFL ratings than were otolaryngologists (2.25 and 3.92, P < .0001). CONCLUSION: Although 4D-CT may be more accurate in assessing the degree of UAO in patients with RS, 4D-CT and FFL assessments demonstrate similar reliability. Additionally, 4D-CT may be interpreted with greater confidence by nonotolaryngologists who care for these patients.

Changes in Hyoid Bone Position Before and After Distraction Osteogenesis in Infants With Robin Sequence.

PURPOSE: To study the changes of hyoid position in infants with Robin sequence before and after mandibular distraction osteogenesis, and to explore the related factors. MATERIAL AND METHODS: Twenty-six infants with Robin sequence underwent bilateral mandibular distraction osteogenesis from May 2016 to April 2020. Three-dimensional computed tomography data of patients before and after surgery were analyzed with Materialise Mimics 17.0. Changes in the three-dimensional position of the hyoid bone were studied. RESULTS: The angle between the long axis of the tongue body and hard palate plane, and the angle between the long axis of the tongue body and mandibular plane were significantly decreased after surgery than before surgery. The hyoid bone-cranial base vertical distance, hyoid bone-mental point distance, and hyoid bone - epiglottis distance were significantly increased after surgery. The differences in the above-mentioned data were statistically significant ( P  < 0.05). Changes in the angle between the long axis of the tongue body and the hyoid bone - mental point line correlated with changes in the position of the hyoid bone relative to the cervical spine ( P   =  0.006). Postoperatively, the hyoid bone moved forward and the increase in the hyoid bone - mental point osseous distance interval (41.28%) was significantly greater than the increase in the hyoid bone-epiglottis distance (18.73%). Differences in the total mandibular length and the hyoid bone - cranial base vertical distance are related to the age at the operation ( P  < 0.05). The younger the age at the time of surgical intervention, the greater the difference before and after surgery for the same follow-up interval. CONCLUSIONS: The three-dimensional direction of the hyoid bone changes after the distraction osteogenesis of the mandible, and the hyoid bone moves downward and forward. Because the mandibular length and airway changed, the relative positions of the long axis of the tongue body on the sagittal plane rotated clockwise.

Spatial Analysis of the Temporomandibular Joint and Condyle Following Mandibular Distraction in Robin Sequence.

ABSTRACT: To comprehensively assess changes in temporomandibular joint and mandibular condyle morphology in Robin sequence (RS) patients undergoing mandibular distraction osteogenesis (MDO). A retrospective analysis of pediatric patients with RS and functional temporomandibular joints who underwent MDO by a single surgeon was performed. Preoperative and postoperative computed tomography (CT) scans were morphometrically analyzed three-dimensional in 3-matic and Mimics (Materialise). Comparative analysis was performed using Wilcoxon signed-rank tests. Fourteen RS patients were included (28 condyles, 56 CT scans), 78% male and 22% females. The mean age at surgery was 9.4 weeks (range 1.6-46.7 weeks). The average age at initial CT was 5.3 days (range 0-11 days). The mean time interval for CT scan before MDO and after hardware removal were 8.8 ±â€Š6.4 days and 11.2 ±â€Š25.8 days, respectively. Rotatory changes of the condyle revealed a significantly decreased horizontal angle following MDO (-7.55°, 95% confidence interval -11.13° to -3.41°; P < 0.001). Anteroposteriorly, the angle between condylar process and ramus (incline) increased significantly (14.14°, 95% confidence interval 10.71°-19.59°; P < 0.001). Intragroup analysis revealed no difference between left versus right condylar position measurements. The condyle itself increased in size and length and the intercondylion distance increased post-MDO. There were no complications and all patients achieved relief of airway obstruction without tracheostomy. Morphologic and positional changes of the mandibular condyle following MDO in RS patients parallel changes that occur during normal development in non-RS patients. As a result, MDO may facilitate normal condylar morphology and function in RS patients.

Effects of Mandibular Distraction Osteogenesis on Three-Dimensional Upper Airway Anatomy in Newborns Affected by Isolated Pierre Robin Sequence.

BACKGROUND: Effective airway management is critical to Pierre Robin Sequence treatment. The goal of this study is to assess the three-dimensional changes in airway size and shape in 117 newborns with isolated Pierre Robin sequence who underwent mandibular distraction osteogenesis. METHODS: During the study period (11/29/2016 to 11/26/2019), 117 newborns affected by isolated Pierre Robin sequence met the inclusion criteria for the present study. All 117 included patients underwent linear distraction. Demographic variables were recorded and analyzed. Cone-beam computed tomography were performed before and after mandibular distraction osteogenesis. A systemic quantitative three-dimensional analysis of size and shape of upper airway was performed. RESULTS: The mean age was 71 day (range 12 to 213). The mean weight was 3.9 kg (range 2.3-6.8). A total of 53 patients are female and 64 are male. When the distraction device was removed, the upper and lower jaws were symmetrically aligned. Pre- and post-distraction comparison clearly showed osteogenesis. For the size of the upper airway, airway volume, anteroposterior dimension of the retroglossal airway, lateral dimension of retroglossal airway, minimum retropalatal area, minimum retroglossal area, average cross-sectional area and minimum cross-sectional area increased significantly after mandibular distraction osteogenesis (P < 0.001). However, the airway length did not change significantly (P > 0.05). For the shape of the upper airway, the lateral/anteroposterior ratio in the retroglossal region and the ratio of the retropalatal airway diameter to the retroglossal airway diameter significantly decreased after mandibular distraction osteogenesis (P < 0.001). The airway uniformity significantly increased after mandibular distraction osteogenesis (P < 0.001). CONCLUSION: Mandibular distraction osteogenesis for isolated Pierre Robin sequence improved size and shape of the upper airway, further confirming mandibular osteogenesis distraction as an effective surgical modality to address the airway obstruction in newborns affected by isolated Pierre Robin sequence. Cone-beam computed tomography scanning and analysis can serve as a safe and effective examination modality for upper airway applications of PRS newborns.

4D Computed Tomography for Dynamic Upper Airway Evaluation in Robin Sequence.

Thorough assessment of dynamic upper airway obstruction (UAO) in Robin sequence (RS) is critical, but traditional evaluation modalities have significant limitations. Four-dimensional computed tomography (4D-CT) is promising in that it enables objective and quantitative evaluation throughout all phases of respiration. However, there exist few protocols or analysis tools to assist in obtaining and interpreting the vast amounts of obtained data. A protocol and set of data analysis tools were developed to enable quantification and visualization of dynamic 4D-CT data. This methodology was applied to a sample case at 2 time points. In the patient with RS, overall increases in normalized airway caliber were observed from 5 weeks to 1 year. There was, however, continued dynamic obstruction at all airway levels, though objective measures of UAO did improve at the nasopharynx and oropharynx. Use of 4D-CT and novel analyses provide additional quantitative information to evaluate UAO in patients with RS.

Orthodontic Management of a Palatal Fistula in a Patient With Pierre Robin Sequence Using 3D Intraoral Scanning and Computer-Aided Design.

Pierre Robin sequence (PRS) is a rare congenital abnormality that may be classified as a first branchial arch syndrome. Patients with PRS who present with cleft palate have a deformity to the soft or hard palate of the maxilla that is repaired within the first year of birth. Despite the repair, patients may experience oronasal complications. Surgical repair is usually necessary if palatal fistula presents, and prosthetic obturators are used to provide temporary relief prior to surgery. This case report outlines the steps in the successful fabrication of a custom-fitted temporary vacuum-formed prosthetic obturator using computer-aided design technology to provide a more comfortable and effective treatment option for the patient.

Floating Bone Phenomenon in Pierre Robin Sequence.

After a failed mandibular osteodistraction, the wrong positioned mandible of a few patients with Pierre Robin sequence returned in the most functional position and regained a proper symmetry, without external intervention. The study aims to explain this self-adjustment and introduce the floating bone phenomenon.The inclusion criteria were severe micrognathia, Fast and Early Mandibular Distraction Osteogenesis protocol, postoperative mandibular wrong positioning, presurgery, immediate postsurgery, and long-term computed tomography scan. Five patients were included. The considered parameters were the distance between mandibular dental centerline and midsagittal facial axis, the rotation of the mandibular body, the magnitude of elongation, and the lowering of the mandibular body.Three patients went from a decentralization >4 mm in the activation phase to a normalization of the said value in the follow-up. In the same period, the interincisal point of 2 patients moved respectively from 0.5 mm on the left and 0.8 mm on the right to 1.2 mm and 1.6 mm on the right, respectively. The rotation of the mandibular body was meanly 25.6° among all patients. The mean value of the distraction was 14.1 mm. A difference of about 4.4 mm between the left and the right side was measured. The lowering of the mandible varied between 2.8 and 12.6 mm.All patients improved their symmetry. Four of them improved in all the measured parameters, while 1 patient presented a worsening in the decentralization of the interincisal point.The floating bone phenomenon could break new grounds in the management of patients with Pierre Robin sequence.

Hyoid Bone Position and Head Posture in Patients With Richieri-Costa Pereira Syndrome (EIF4A3 Mutations).

Robin sequence with cleft mandible and limb anomalies, known as Richieri-Costa-Pereira syndrome (RCPS), is an autosomal recessive acrofacial dysostosis characterized by mandibular cleft and other craniofacial anomalies and respiratory complications. The aim of this cross-sectional study was to describe the hyoid and head posture of 9 individuals with RCPS using cephalometric measurements and provide a discussion about its implications in obstructive sleep apnea syndrome (OSAS). The study was conducted on lateral cephalograms of patients with RCPS and 9 selected age-matched controls in tertiary cleft center in Brazil. The cephalograms were digitized and analyzed on a software to obtain the vertical and horizontal hyoid position, its relationship with the mandible and the relation of the cranial base and postvertebral line. The t test was used for analysis of means and Levene's test for equality of variances.Cephalometric measurements H-S (vertical distance between hyoid bone and sella) (Supplemental Digital Content, Figure 1, http://links.lww.com/SCS/B247) and H-C4lp (horizontal position of the hyoid in relation to the post-pharyngeal space) showed statistically significant difference compared to controls (P < 0.05). Therefore, the hyoid bone was more inferiorly and posteriorly positioned in the study group compared with the control group. The vertebrae measurements did not present differences compared to controls. The described position of hyoid bone could be involved in the severe OSAS of RCPS patients.

An Intraoperative Salvage After Transection of the Greater Palatine Artery During Cleft Palate Repair: A Case for Buccal Fat and Buccal Myomucosal Flaps.

Recently, several adjunctive procedures have gained traction to aid cleft surgeons in repairing especially challenging palatal clefts. Buccal fat flaps and buccal myomucosal flaps have demonstrated particular utility in reinforcing thin palatal flaps or tissue deficits. Although their use has not been widely accepted, they may be particularly helpful in the setting of significant scarring or vascular compromise. Here the authors describe the case of an intraoperative salvage using bilateral buccal fat flaps and a right buccal myomucosal flap after transection of the right Greater Palatine artery (GPA) during palatoplasty on a 14-month old female with Pierre Robin Sequence and a wide Veau II cleft palate. For this operative salvage, bilateral buccal fat flaps were used to reinforce the hard-soft palate junction and a 4 cm × 2 cm flap of the right-sided buccal mucosa and buccinator muscle was inset along the majority of the right-sided soft and posterior hard palate. At 2 years follow-up, the patient had no significant complications and was doing well with healthy-appearing palatal tissue and age-appropriate speech.

Dynamical Changes of Mandible and Upper Airway After Mandibular Distraction Osteogenesis in Pierre Robin Sequence.

OBJECTIVE: To present the dynamical evaluation of mandible and upper airway size among Chinese infant patients following mandibular distraction osteogenesis in a short-term follow-up and compare predistraction measurements with a normal age- and sex-matched control. METHODS: All the patients have undergone the computed tomography (CT) scan before mandibular distraction osteogenesis (T0), at the end of the distraction phase (T1), and 3 months after the end of the distraction phase before the distractor removal (T2). A CT analyzing computer software MIMICS was utilized to analyze the anatomic variables of upper airway size and mandible size. All analysis was based on a significance level of 0.05. RESULTS: Eight patients with Pierre Robin sequence differed mainly in the mandibular body length and the minimum anteroposterior dimension of the retroglossal airway from the control. After mandibular distraction osteogenesis, the mandibular body length and the ramus height both increased significantly, the ramus height also increased after 3 months of consolidation. Only small increase in the airway dimension of the retroglossal area at T2 was observed compared with T1. CONCLUSION: Mandibular distraction osteogenesis is an effective modality in treating Pierre Robin sequence. Compared with normal control, the main difference may be the length of mandibular body and the area of the retroglossal airway. There may not be an increase in the diameter of airway and the length of mandibular body after 3 months of growth and development in Pierre Robin sequence. Individual surgical plan should be made to gain a better prognosis.

The use of three-dimensional reconstructions of CT scans to evaluate anomalies of hyoid bone in Pierre Robin sequence: A retrospective study.

AIM: The aim of the study was to investigate hyoid bone anomalies in patients with Pierre Robin sequence (PRS) compared to the control group, using computed tomography (CT) examination and three-dimensional reconstruction of the hyoid bone and mandible. METHODS: A retrospective study was performed of patients between birth and 12 months old with isolated PRS (i-PRS) and syndromic PRS (ni-PRS), who had undergone CT examination, and whose results were compared to the control group of the same age. DICOM data was processed to highlight bone tissue. The mandible and hyoid bones were the main targets of the three-dimensional reconstruction. The study outcomes were the analysis of hyoid bone ossification, volume, and position (distance between hyoid and mandibular symphysis). Univariate and multivariate statistical analyses were performed with α=0.05 as level of significance. RESULTS: The study sample included 29 i-PRS and 21 ni-PRS patients, while 43 infants in the control group. Hyoid ossification was present in 26/50 (52%) PRS patients (14 i-PRS; 12 ni-PRS) but in 31/43 controls (72%). Statistical analysis showed that absence of hyoid ossification was significantly associated with the diagnosis of PRS (P<0.05). Only ni-PRS patients showed a significant reduction of the distance between hyoid and mandible compared to the control group (P<0.001). Hyoid volume was significantly lower only in the ni-PRS group than in controls (P<0.001). CONCLUSION: I-PRS and ni-PRS patients differ both etiologically and clinically. Ni-PRS patients confirmed their worst clinical condition than i-PRS with severe anomalies of hyoid development, helping for their ontogeny classification.

Case report of neonate Pierre Robin sequence with severe upper airway obstruction who was rescued by finger guide intubation.

BACKGROUND: Pierre Robin Sequence (PRS) patients are known for their triad of micrognathia, glossoptosis, and airway obstruction. Their airway can be a challenge even for the most experienced pediatric anesthesiologist. CASE PRESENTATION: We report the case of a 9 day old 3.5 kg boy diagnosed with PRS, cleft palate, and a vallecular cyst with severe upper airway obstruction. The combination of PRS, cleft palate and the presence of vallecular cyst made this a cascade reaction of difficult airway. Due to his unique anatomy, we didn't appreciate how difficult his airway was until multiple attempts with high-tech equipment failed. Ultimately it was the finger guide intubation, this old technique without any equipment, that rescued this patient from lose of airway. CONCLUSIONS: The boy was successfully rescued by finger guided intubation. Finger guide intubation should be added to the anesthesiologist's newborn rescue intubation training.

Risk Factors for Perioperative Respiratory Failure following Mandibular Distraction Osteogenesis for Micrognathia: A Retrospective Cohort Study.

BACKGROUND: The frequency of respiratory events in the perioperative period, and optimal duration of intubation during early mandibular distraction osteogenesis activation, are poorly understood. This study assesses potential risk factors associated with perioperative respiratory events, particularly the need for reintubation, following mandibular distraction osteogenesis surgery. METHODS: A retrospective review was conducted for infants (younger than 1 year) undergoing mandibular distraction osteogenesis for tongue-based airway obstruction between November of 2010 and December of 2017. Univariate and multivariate analyses of sentinel events and outcomes were performed. RESULTS: Ninety infants (median age, 35 days) were included (50 percent were syndromic). Twenty-seven subjects (30 percent) experienced a respiratory event requiring intervention before discharge, including 14 subjects who failed initial extubation. Subjects extubated earlier than postoperative day 5 failed extubation more frequently (33%) compared to those extubated later (9%; p = 0.005). Respiratory events occurred more frequently when extubation was attempted at distraction lengths of 5 mm or less (42 percent) compared to greater than 5 mm (21 percent; p = 0.032). Logistic regression modeling showed that syndromic status (OR, 14.8) and secondary airway anomaly (OR, 6.1) were significant predictors for respiratory events, whereas greater length of distraction at the time of extubation was protective (OR, 0.8; p < 0.05). CONCLUSIONS: Postoperative intubation of at least 5 days with associated mean distraction of 5 mm appears to be associated with successful extubation trial following mandibular distraction osteogenesis surgery. Patients with congenital syndromes and secondary airway anomalies are more likely to experience perioperative respiratory events. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Three-dimensional printing of surgical guides for mandibular distraction osteogenesis in infancy.

Pierre Robin sequence (PRS) is a congenital malformation characterized by micrognathia, glossocoma, and mechanical obstruction of the upper respiratory tract. These deformities impair respiration, sleep, feeding, and swallowing, and can lead to malnutrition, stunted development, and death. Bilateral mandibular distraction osteogenesis, whereby the mandible and tongue root are extended outward, is the standard treatment to relieve upper airway obstruction in severe PRS. Accurate placement of the distraction device is essential but challenging, especially in infants, and requires the pre-operative fabrication of surgical guides based on CT images. Three-dimensional (3D) printing allows for the accurate recreation of objects from digitized models. We compared surgical efficacy and safety of bilateral mandibular distraction osteogenesis using 3D printed or traditionally fabricated surgery guides for treatment of infants with severe PRS.During the period from 2014 to 2016, 22 patients with severe PRS were treated using either traditional or 3D printed surgery guides. We compared outcome measures of operations, including intraoperative bleeding, operation time, and postoperative complications.The 3D printed surgery guide group demonstrated significantly shorter operation time (P <.05) as well as moderately shorter hospital stay and artificial ventilation time (∼1 day less). Furthermore, despite markedly younger average age of the 3D printed group (1.3 vs 3.5 months), there was no increase in postoperative complications using the 3D printed guides.Three-dimensional printed surgery guides were used successfully for bilateral mandibular traction osteogenesis, and according to several outcome, parameters demonstrated superior efficacy and safety compared to traditional guides. Further research is warranted to extend the applications of 3D printed surgical guides for craniofacial surgery.

Novel dental phenotype in non-syndromic Pierre Robin Sequence: A retrospective study.

OBJECTIVE: The objective was to investigate dental phenotypes in individuals with non-syndromic Pierre Robin Sequence (ns-PRS) and compare the prevalence of these phenotypes with subjects with non-syndromic cleft palate (ns-CP) and a control group with subjects without any craniofacial anomalies. METHODS: A total of 760 panoramic radiographs of 330 individuals (110 with ns-PRS; 110 with ns-CP and 110 without any malformations) were digitized and evaluated regarding the diagnosis of taurodontism, tooth agenesis, root dilaceration and tooth transposition. Chi-square test was applied to compare the occurrence of dental phenotypes between groups. A P value of less than 0.05 was considered statistically significant. RESULTS: Total prevalence of dental phenotypes was 94.5% of ns-PRS; 54.5% of ns-CP and 59.1% of the control group subjects with a statistically significant difference for the ns-PRS when compared to the other two groups. Two dental phenotypes, taurodontism and dental agenesis were identified with statistically significant higher prevalences in subjects with ns-PRS when compared with the ns-CP group and the control group (p < 0.001). Taurodontism was the most prevalent dental phenotype, with 92.73% in the ns-PRS group, 40.91% for ns-CP and 44.55% in the control group. Tooth agenesis had a prevalence of 22.7% for ns-PRS, 4.5% for ns-CP and no case in the control group. For the prevalence of root dilaceration and tooth transposition, no statistically significant differences were observed between the three groups. CONCLUSIONS: Due to the high frequency of taurodontism in individuals with ns-PRS, we suggested that this novel phenotype would be important in the phenotypic screening of ns-PRS and could be considered as a phenotype associated with ns-PRS.