Stephen A. Schendel

An architectural and structural craniofacial analysis: a new lateral cephalometric analysis.

The architectural and structural craniofacial analysis is based upon mutual balance of the cranial and facial bony structures. With this technique, the bases and calvaria of the cranium and then the face can be studied successively in relation to the cranium and craniospinal articulation. Statistical averages are avoided, and individual proportions influenced by the unique features of each skeleton are relied upon. The dentition is placed within the cephalic context, and therapy etiologic factors of dentofacial dysmorphoses which would not otherwise be demonstrated by conventional analysis are made obvious. This technique is particularly useful to the maxillofacial surgeon, as it clearly demonstrates all of the maxillofacial deformities and the pathologic balances that need to be corrected. In severe craniofacial malformations, it offers better possibilities than other cephalometric analysis methods of detecting the various cranial and facial anomalies which characterize these conditions.

Studies in cranial suture biology : up-regulation of transforming growth factor-beta1 and basic fibroblast growth factor mRNA correlates with posterior frontal cranial suture fusion in the rat

&NA; The mechanisms involved in normal cranial suture development and fusion as well as in the pathophysiology of craniosyostosis are not well understood. The purpose of this study was to investigate the expression of several cytokines—transforming growth factor‐beta‐1 (TGF‐&bgr;1), basic fibroblast growth factor (bFGF), and interleukin‐6 (IL‐6)—during cranial suture fusion. TGF‐&bgr; exists in three mammalian isoforms that are abundant in bone and stimulate calvarial bone formation when delivered locally. Other bone growth factors including basic fibroblast growth factor and the interleukins regulate bone growth and are mitogenic for bone marrow cells and osteoblasts. The involvement of growth factors in the pathophysiology of craniosynostosis is supported by recent genetics data linking fibroblast growth factor receptor mutations to syndromal craniosynostoses. In this experimental study, in situ hybridization was used to localize and quantify the gene expression of TGF‐&bgr;1, bFGF, and IL‐6 during cranial suture fusion. In the Sprague‐Dawley rat, the posterior frontal cranial suture normally undergoes fusion between 12 and 22 days of age, whereas all other cranial sutures remain patent. All in situ analyses of fusing posterior frontal sutures were compared with the patent, control, sagittal sutures. Posterior frontal and sagittal sutures, together with underlying dura, were harvested from rats at 8, 12, 16, and 35 days of postnatal life to analyze posterior frontal suture activity before, during, and after fusion. In situ hybridization was performed on frozen sections of these specimens using DNA probes specific for TGF‐&bgr;1, bFGF, and IL‐6 mRNA. A negative control probe to IL‐6 in the sense orientation was also used to validate the procedure. Cells expressing cytokine‐specific mRNA were quantified (in cells positive per 10‐1 mm2) and analyzed using the unpaired Students t test. Areas encompassing the fibrous suture and the surrounding bone plates were analyzed for cellular mRNA activity. IL‐6 mRNA expression showed a minimal rise in the posterior frontal suture at days 12 and 16, with an average count of 10 and 6 cells per 10‐1 mm2, respectively. The sagittal suture remained negative for IL‐6 mRNA at all time points. TGF‐&bgr;1 and bFGF analyses were most interesting, showing marked increases specifically in the posterior frontal suture during the time of active suture fusion. On postnatal day 8, a 1.5‐fold increase in posterior frontal suture TGF‐&bgr;1 mRNA was found compared with sagittal sutures (p = 0.1890, unpaired Students t test). This difference was increased 26‐fold on day 12 in posterior frontal suture TGF‐&bgr;1 expression (p = 0.0005). By day 35, posterior frontal suture TGF‐&bgr;1 mRNA had nearly returned to prefusion levels, whereas TGF‐&bgr;1 mRNA levels in the sagittal suture remained low. A similar upregulation of bFGF mRNA, peaking at day 12, was observed in posterior frontal but not sagittal sutures (p = 0.0003). Furthermore, both TGF‐&bgr;1 and bFGF mRNA samples with intact dura showed an intense dural mRNA expression in the time preceding and during active posterior frontal suture fusion but not in sagittal tissues. Our data demonstrate that TGF‐&bgr;1 and bFGF mRNA are up‐regulated in cranial suture fusion, possibly signaling in a paracrine fashion from dura to suture. TGF‐&bgr;1 and bFGF gene expression were dramatically increased both in and surrounding the actively fusing suture and followed the direction of fusion from endocranial to epicranial. These experimental data on bone growth factors support the recent human genetics data linking growth factor/fibroblast growth factor receptor deletions to syndromal craniosynostoses. The ultimate aim of these studies is to understand the underlying mechanisms regulating suture growth, development, and fusion so surgeons may one day manipulate the biology of premature cranial suture fusion. (Plast. Reconstr. Surg. 101: 1431, 1998.)

Facial changes associated with surgical advancement of the lip and maxilla

A study of maxillary advancements performed with concomitant nasolabial muscle reconstruction demonstrated a predictable soft tissue/osseous ratio of 1:0.9, with the lip moving forward on the average of 90% of the dentition. Lip shortening was not found in this group of patients.

Muscle reorientation following superior repositioning of the maxilla.

In facial reconstructive surgery the importance of the orofacial muscles on form, function, and esthetics must be recognized. Once this fact is acknowledged, these muscles may be manipulated to advantage by the surgeon; thus, undesirable effects in the perioral area following superior repositioning of the maxilla can be avoided. A V-Y advancement-closure of the horizontal maxillary vestibular incision is advocated. This successfully repositions the lip muscles in a predictable manner and maintains normal lip form pout, and amount of exposed vermilion. Alar width and unesthetic widening of the alar bases may also be controlled by the proper repositioning of the transverse nasalis muscles. The validity of these surgical procedures is supported by a statistical analysis of the lip and nasal structures in patients whose dentofacial deformities were corrected by superior repositioning of the maxilla and concomitant facial muscle reorientation.

Automated 3-dimensional airway analysis from cone-beam computed tomography data.

p a o m m l a s s a p s l o w h p he analysis and 3-dimensional (3D) imaging of the irway have become more common as technological evelopments in both imaging and computer analysis ave advanced and converged during the past few ears. These advances have been especially beneficial or the ability to understand and diagnose obstructed leep disordered breathing (OSDB) and its relationship o the craniofacial anatomy. The improved availability of one-beam computed tomography (CBCT), 3D imaging, nd computer simulation in dentofacial analysis and reatment planning has facilitated the use of this method or evaluation of the airway. The currently available iagnosis and treatment planning methods for OSDB ave limitations despite inclusion of the patient’s sleep istory, nasendoscopy, polysomnography, and convenional imaging. A precise anatomic analysis of the airway hat could be correlated with the severity of OSDB and e easily obtainable would be valuable for diagnosis and reatment planning. At present, the airway calculation rom computed tomography data requires time-consumng manual data segmentation, the accuracy of which ould be questionable. Automatic data segmentation has he ability to provide rapid and reliable airway analysis esults. The airway extending from the tip of the nose to he epiglottis can be visualized on the CBCT scan Fig 1). Because the scan also includes the jaws, teeth, ranial base, spine, and facial soft tissues, there is an pportunity to evaluate the functional and developental relationships among these structures. The

Airway Growth and Development: A Computerized 3-Dimensional Analysis

PURPOSE The present study was undertaken to investigate the changes in the normal upper airway during growth and development using 3-dimensional computer analysis from cone-beam computed tomography (CBCT) data to provide a normative reference. METHODS The airway size and respiratory mode are known to have a relationship to facial morphology and the development of a malocclusion. The use of CBCT, 3-dimensional imaging, and automated computer analysis in treatment planning allows the upper airway to be precisely evaluated. In the present study, we evaluated the growth of the airway using 3-dimensional analysis and CBCT data from age 6 through old age, in 1300 normal individuals. RESULTS The airway size and length increase until age 20 at which time a variable period of stability occurs. Next, the airway at first decreases slowly in size and then, after age 40, more rapidly. Normative data are provided in the present study for age groups from 6 to 60 years in relation to the airway total volume, smallest cross-sectional area and vertical length of the airway. CONCLUSIONS This 3-dimensional data of the upper airway will provide a normative reference as an aid in the early understanding of respiration and dentofacial anatomy, which will help in early treatment planning.

An analysis of Le Fort I maxillary advancement in cleft lip and palate patients

We present a series of 24 consecutive cleft lip and palate patients aged 16 to 46 years (mean age 27 years) who underwent Le Fort I maxillary advancement by the senior author over the past 8 years. Two groups, one of 12 patients with wire fixation and one of 12 patients with miniplate fixation, were evaluated. Each group had 10 unilateral and 2 bilateral clefts. All patients were grafted with autogenous bone (8 cranial, 14 iliac, and 2 mandibular). Horizontal advancement was 3 mm to 2 cm (with a mean of 7.8 mm). Vertical movement ranged from a shortening of 5 mm to a lengthening of 1.3 cm (mean 2.3 mm of lengthening). The amount and timing of relapse were compared in both the horizontal and vertical dimensions. The plated group was more stable in both the horizontal and vertical dimensions (p < 0.05). No significant skeletal relapses occurred after the first year. Statistically significant dental relapse occurred only in the wired group. Three patients developed transverse collapse of the small maxillary cleft segment, and four developed incisor angulation to compensate for maxillary skeletal relapse. The presence of a pharyngeal flap at the time of advancement appeared to increase relapse in both horizontal and vertical dimensions (p < 0.03), but there were too few patients (7 of 24) with pharyngeal flaps to prove this conclusively. We also concluded that pterygomandibular grafting is not necessary to achieve excellent results using miniplate fixation; autogenous grafting of the anterior maxillary osteotomy alone provides the necessary stability.

Nasal considerations in orthognathic surgery

The functional correction of dentofacial deformities by orthognathic surgery produces major changes in facial appearance. Facial esthetics must therefore be equally appreciated by the orthodontist and the maxillofacial surgeon. The orthodontist must perform a thorough esthetic facial evaluation along with his usual orthodontic evaluation. The treatment plan must then be based on the esthetic evaluation and knowledge of the facial changes caused by orthodontic treatment and skeletal jaw surgery. Central to facial form is the nose. This article will outline the proper functional and esthetic evaluation of the nose in relation to the face. Nasal and upper lip changes associated with maxillary procedures will also be covered in detail. In light of these two areas, proper treatment planning and sequencing will be discussed.

Maxillary, Mandibular, and Chin Advancement: Treatment Planning Based on Airway Anatomy in Obstructive Sleep Apnea

Surgical correction of obstructive sleep apnea (OSA) syndrome involves understanding a number of parameters, of which the 3-dimensional airway anatomy is important. Visualization of the upper airway based on cone beam computed tomography scans and automated computer analysis is an aid in understanding normal and abnormal airway conditions and their response to surgery. The goal of surgical treatment of OSA syndrome is to enlarge the velo-oropharyngeal airway by anterior/lateral displacement of the soft tissues and musculature by maxillary, mandibular, and possibly, genioglossus advancement. Knowledge of the specific airway obstruction and characteristics based on 3-dimensional studies permits a directed surgical treatment plan that can successfully address the area or areas of airway obstruction. The end occlusal result can be improved when orthodontic treatment is combined with the surgical plan. The individual with OSA, though, is more complicated than the usual orthognathic patient, and both the medical condition and treatment length need to be judiciously managed when OSA and associated conditions are present. The perioperative management of the patient with OSA is more complex and the margin for error is reduced, and this needs to be taken into consideration and the care altered as indicated.

The role of suprahyoid myotomy in surgical advancement of the mandible via sagittal split ramus osteotomies

Abstract The suprahyoid muscles have been implicated as primary effectors of relapse following surgical advancement of the deficient mandible. Accordingly, suprahyoid myotomy and/or the use of cervical collars have been recommended as adjunctive procedures to minimize postoperative relapse. This computerized morphometric evaluation of 16 patients revealed that suprahyoid myotomy is not essential to skeletal stability following surgical advancement of the mandible.