How does mandibular advancement with or without maxillary procedures affect pharyngeal airways? An overview of systematic reviews.
ABSTRACT: Mandibular advancement surgery may positively affect pharyngeal airways and therefore potentially beneficial to obstructive sleep apnea (OSA).To collect evidence from published systematic reviews that have evaluated pharyngeal airway changes related to mandibular advancement with or without maxillary procedures.PubMed, EMBASE, Web of Science, and Cochrane Library were searched without limiting language or timeline. Eligible systematic reviews evaluating changes in pharyngeal airway dimensions and respiratory parameters after mandibular advancement with or without maxillary surgery were identified and included.This overview has included eleven systematic reviews. Maxillomandibular advancement (MMA) increases linear, cross-sectional plane and volumetric measurements of pharyngeal airways significantly (p<0.0001), while reducing the apnea-hypopnea index (AHI) and the respiratory disturbance index (RDI) significantly (p<0.0001). Two systematic reviews included primary studies that have evaluated single-jaw mandibular advancement, but did not discuss their effect onto pharyngeal airways. Based on the included primary studies of those systematic reviews, single-jaw mandibular advancement was reported to significantly increase pharyngeal airway dimensions (p<0.05); however, conclusive long-term results were lacking.MMA increases pharyngeal airway dimensions and is beneficial to patients suffering from OSA. However, more evidence is still needed to draw definite conclusion related to the effect of single-jaw mandibular advancement osteotomies on pharyngeal airways.
Project description:Mandibular setback osteotomies potentially lead to narrowing of the pharyngeal airways, subsequently resulting in post-surgical obstructive sleep apnea (OSA).To summarize current evidence from systematic reviews that has evaluated pharyngeal airway changes after mandibular setback with or without concomitant upper jaw osteotomies.PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched with no restriction of language or date. Systematic reviews studying changes in pharyngeal airway dimensions and respiratory parameters after mandibular setback with or without concomitant upper jaw osteotomies have been identified, screened for eligibility, included and analyzed in this study.Six systematic reviews have been included. While isolated mandibular setback osteotomies result in reduced oropharyngeal airway dimensions, the reduction is lesser in cases with concomitant upper jaw osteotomies. Only scarce evidence exists currently to what happens to naso- and hypo-pharyngeal airways. There is no evidence for post-surgical OSA, even though some studies reported reduced respiratory parameters after single-jaw mandibular setback with or without concomitant upper jaw osteotomies.Although mandibular setback osteotomies reduce pharyngeal airway dimensions, evidence confirming post-surgical OSA was not found. Nevertheless, potential post-surgical OSA should be taken into serious consideration during the treatment planning of particular orthognathic cases. As moderate evidence exists that double-jaw surgeries lead to less compromised post-surgical pharyngeal airways, they should be considered as the method of choice especially in cases with severe dentoskeletal Class III deformity.PROSPERO (registration number: CRD42016046484).
Project description:Maxillomandibular advancement (MMA) is effective for the treatment of obstructive sleep apnea (OSA). In previous studies, the airway was increased in the anteroposterior and transverse dimensions after MMA. However, the effect of the opposite of mandibular movement (mandibular setback) on the airway is still controversial. Mandibular setback surgery has been suggested to be one of the risk factors in the development of sleep apnea. Previous studies have found that mandibular setback surgery could reduce the total airway volume and posterior airway space significantly in both the one-jaw and two-jaw surgery groups. However, a direct cause-and-effect relationship between the mandibular setback and development of sleep apnea has not been clearly established. Moreover, there are only a few reported cases of postoperative OSA development after mandibular setback surgery. These findings may be attributed to a fundamental difference in demographic variables such as age, sex, and body mass index (BMI) between patients with mandibular prognathism and patients with OSA. Another possibility is that the site of obstruction or pattern of obstruction may be different between the awake and sleep status in patients with OSA and mandibular prognathism. In a case-controlled study, information including the BMI and other presurgical conditions potentially related to OSA should be considered when evaluating the airway. In conclusion, the preoperative evaluation and management of co-morbid conditions would be essential for the prevention of OSA after mandibular setback surgery despite its low incidence.
Project description:Articulated jaws are highly conserved structures characteristic of gnathostome evolution. Epithelial-mesenchymal interactions within the first pharyngeal arch (PA1) instruct cephalic neural crest cells (CNCCs) to form the different skeletal elements of the jaws. The endothelin-1 (Edn1)/endothelin receptor type-A (Ednra)-->Dlx5/6-->Hand2 signaling pathway is necessary for lower jaw formation. Here, we show that the Edn1 signaling is sufficient for the conversion of the maxillary arch to mandibular identity. Constitutive activation of Ednra induced the transformation of upper jaw, maxillary, structures into lower jaw, mandibular, structures with duplicated Meckel's cartilage and dermatocranial jaws constituted by 4 dentary bones. Misexpression of Hand2 in the Ednra domain caused a similar transformation. Skeletal transformations are accompanied by neuromuscular remodeling. Ednra is expressed by most CNCCs, but its constitutive activation affects predominantly PA1. We conclude that after migration CNCCs are not all equivalent, suggesting that their specification occurs in sequential steps. Also, we show that, within PA1, CNCCs are competent to form both mandibular and maxillary structures and that an Edn1 switch is responsible for the choice of either morphogenetic program.
Project description:Two-jaw surgery including mandibular and maxillary backward movement procedures are commonly performed to correct class III malocclusion. Bimaxillary surgery can reposition the maxillofacial bone together with soft tissue, such as the soft palate and the tongue base. We analyzed changes of pharyngeal airway narrowing to ascertain clinical correlations with the prevalence of snoring after two-jaw surgery.A prospective clinical study was designed including a survey on snoring and three-dimensional (3D) computed tomography (CT) in class III malocclusion subjects before and after bimaxillary surgery. We conducted an analysis on changes of the posterior pharyngeal space find out clinical correlations with the prevalence of snoring.Among 67 subjects, 12 subjects complained about snoring 5 weeks after the surgical correction, and examining the 12 subjects after 6 months, 6 patients complained about the snoring. The current findings demonstrated the attenuation of the largest transverse width (LTW), anteroposterior length (APL), and cross-sectional area (CSA) following bimaxillary surgery given to class III malocclusion patients, particularly at the retropalatal level. The average distance of maxillary posterior movements were measured to be relatively higher (horizontal distance 3.9 mm, vertical distance 2.6 mm) in case of new snorers.This study found that bimaxillary surgery could lead to the narrowing of upper airway at the retropalatal or retroglossal level as well as triggering snoring in subjects with class III malocclusion. Based on the current clinical findings, we also found that upper airway narrowing at retropalatal level may contribute to increasing the probability of snoring and that polysonography may need to be performed before orthognathic surgery in subjects with class III malocclusion.
Project description:STUDY OBJECTIVES: To characterize tongue and lateral upper airway movement and to image tongue deformation during mandibular advancement. DESIGN: Dynamic imaging study of a wide range of apnea hypopnea index (AHI), body mass index (BMI) subjects. SETTING: Not-for-profit research institute. PARTICIPANTS: 30 subjects (aged 31-69 y, AHI 0-75 events/h, BMI 17-39 kg/m(2)). INTERVENTIONS: Subjects were imaged using dynamic tagged magnetic resonance imaging during mandibular advancement. Tissue displacements were quantified with the harmonic phase technique. MEASUREMENTS AND RESULTS: Mean mandibular advancement was 5.6 ± 1.8 mm (mean ± standard deviation). This produced movement through a connection from the ramus of the mandible to the pharyngeal lateral walls in all subjects. In the sagittal plane, 3 patterns of posterior tongue deformation were seen with mandibular advancement-(A) en bloc anterior movement, (B) anterior movement of the oropharyngeal region, and (C) minimal anterior movement. Subjects with lower AHI were more likely to have en bloc movement (P = 0.04) than minimal movement. Antero-posterior elongation of the tongue increased with AHI (R = 0.461, P = 0.01). Mean anterior displacements of the posterior nasopharyngeal and oropharyngeal regions of the tongue were 20% ± 13% and 31% ± 17% of mandibular advancement. The posterior tongue compressed 1.1 ± 2.2 mm supero-inferiorly. CONCLUSIONS: Mandibular advancement has two mechanisms of action which increase airway size. In subjects with low AHI, the entire tongue moves forward. Mandibular advancement also produces lateral airway expansion via a direct connection between the lateral walls and the ramus of the mandible. CITATION: Brown EC; Cheng S; McKenzie DK; Butler JE; Gandevia SC; Bilston LE. Tongue and lateral upper airway movement with mandibular advancement. SLEEP 2013;36(3):397-404.
Project description:In recent years, bimaxillary rotation advancement (BRA) has become the method of choice for surgical treatment of obstructive sleep apnea (OSA). As dislocation of the jaw bones affects both, airways and facial contours, surgeons are facing the challenge of finding an optimal jaw position that allows for the reestablishment of normal airway ventilation and esthetic surgical outcome. Owing to the complexity of the facial anatomy and its mechanical behavior, individual planning of surgical OSA treatment under consideration of functional and esthetic aspects presents a challenge that surgeons typically approach in a non-quantitative manner using subjective evaluation and clinical experience. This paper describes a framework for individual planning of OSA treatment using bimaxillary rotation advancement, which relies on computational modeling of hard and soft tissue mechanics. The described framework for simulation of functional and esthetic post-surgery outcome was used in 10 OSA patients. Comparison of the simulation results with post-surgery data reveals that biomechanical simulation provides a reliable estimate for post-surgery facial tissue behavior and antero-posterior airway extension, but fails to accurately describe a surprisingly large lateral stretch of the velopharyngeal region. This discrepancy is traced back to anisotropic effects of pharyngeal muscles. Possible approaches to improving the accuracy of model predictions and defining sharp criteria for optimizing combined OSA planning are discussed.
Project description:Gnathostome jaws derive from the first pharyngeal arch (PA1), a complex structure constituted by Neural Crest Cells (NCCs), mesodermal, ectodermal and endodermal cells. Here, to determine the regionalized morphogenetic impact of Dlx5/6 expression, we specifically target their inactivation or overexpression to NCCs. NCC-specific Dlx5/6 inactivation (NCC?Dlx5/6) generates severely hypomorphic lower jaws that present typical maxillary traits. Therefore, differently from Dlx5/6 null-embryos, the upper and the lower jaws of NCC?Dlx5/6 mice present a different size. Reciprocally, forced Dlx5 expression in maxillary NCCs provokes the appearance of distinct mandibular characters in the upper jaw. We conclude that: (1) Dlx5/6 activation in NCCs invariably determines lower jaw identity; (2) the morphogenetic processes that generate functional matching jaws depend on the harmonization of Dlx5/6 expression in NCCs and in distinct ectodermal territories. The co-evolution of synergistic opposing jaws requires the coordination of distinct regulatory pathways involving the same transcription factors in distant embryonic territories.
Project description:Morphogenesis of the vertebrate head relies on proper dorsal-ventral (D-V) patterning of neural crest cells (NCC) within the pharyngeal arches. Endothelin-1 (Edn1)-induced signaling through the endothelin-A receptor (Ednra) is crucial for cranial NCC patterning within the mandibular portion of the first pharyngeal arch, from which the lower jaw arises. Deletion of Edn1, Ednra or endothelin-converting enzyme in mice causes perinatal lethality due to severe craniofacial birth defects. These include homeotic transformation of mandibular arch-derived structures into more maxillary-like structures, indicating a loss of NCC identity. All cranial NCCs express Ednra whereas Edn1 expression is limited to the overlying ectoderm, core paraxial mesoderm and pharyngeal pouch endoderm of the mandibular arch as well as more caudal arches. To define the developmental significance of Edn1 from each of these layers, we used Cre/loxP technology to inactivate Edn1 in a tissue-specific manner. We show that deletion of Edn1 in either the mesoderm or endoderm alone does not result in cellular or molecular changes in craniofacial development. However, ectodermal deletion of Edn1 results in craniofacial defects with concomitant changes in the expression of early mandibular arch patterning genes. Importantly, our results also both define for the first time in mice an intermediate mandibular arch domain similar to the one defined in zebrafish and show that this region is most sensitive to loss of Edn1. Together, our results illustrate an integral role for ectoderm-derived Edn1 in early arch morphogenesis, particularly in the intermediate domain.
Project description:Jaw morphogenesis is a complex event mediated by inductive signals that establish and maintain the distinct developmental domains required for formation of hinged jaws, the defining feature of gnathostomes. The mandibular portion of pharyngeal arch 1 is patterned dorsally by Jagged-Notch signaling and ventrally by endothelin receptor A (EDNRA) signaling. Loss of EDNRA signaling disrupts normal ventral gene expression, the result of which is homeotic transformation of the mandible into a maxilla-like structure. However, loss of Jagged-Notch signaling does not result in significant changes in maxillary development. Here we show in mouse that the transcription factor SIX1 regulates dorsal arch development not only by inducing dorsal Jag1 expression but also by inhibiting endothelin 1 (Edn1) expression in the pharyngeal endoderm of the dorsal arch, thus preventing dorsal EDNRA signaling. In the absence of SIX1, but not JAG1, aberrant EDNRA signaling in the dorsal domain results in partial duplication of the mandible. Together, our results illustrate that SIX1 is the central mediator of dorsal mandibular arch identity, thus ensuring separation of bone development between the upper and lower jaws.
Project description:The jaw is central to the extensive variety of feeding and predatory behaviors across vertebrates. The bones of the lower but not upper jaw form around an early-developing cartilage template. Whereas Endothelin1 patterns the lower jaw, the factors that specify upper-jaw morphology remain elusive. Here, we identify Nuclear Receptor 2f genes (Nr2fs) as enriched in and required for upper-jaw formation in zebrafish. Combinatorial loss of Nr2fs transforms maxillary components of the upper jaw into lower-jaw-like structures. Conversely, nr2f5 misexpression disrupts lower-jaw development. Genome-wide analyses reveal that Nr2fs repress mandibular gene expression and early chondrogenesis in maxillary precursors. Rescue of lower-jaw defects in endothelin1 mutants by reducing Nr2f dosage further demonstrates that Nr2f expression must be suppressed for normal lower-jaw development. We propose that Nr2fs shape the upper jaw by protecting maxillary progenitors from early chondrogenesis, thus preserving cells for later osteogenesis.