6.1 NEED FOR THE STUDY: Orthognathic surgery has been regularly used to treat dentofacial deformities. The surgical procedures affects both the facial appearance as well as posterior airway space hence prior estimation of pharyngeal space would lead to precise estimation of the possible changes that would occur.
Surgical alterations in the position of the bony facial skeleton will inevitably affect the soft tissue – hard tissue relationships. However an aspect of orthognathic surgery that is seldom considered is the effect of skeletal movements on pharyngeal airway. Changes in airway dimensions have been demonstrated after surgical repositioning of maxilla and mandible.
Case reports of mandibular setback surgery including sleep-related breathing disorders , such as obstructive sleep apnoea, have been demonstrated with airway narrowing, Also case reports of Decreased quality of speech, Changes in tongue posture, Changes in level of hyoid bone and Head posture have also been recorded with mandibular set back.
Conventionally, Digitalized Lateral Cephalometric examinations were done to predict the pre-operative and post operative set back or advancement of maxilla and mandible. These examinations had their own disadvantage one of which is being Uni-dimensional.
Naso-endoscopy/ Bronchoscopy is an excellent adjunct for measuring pharyngeal dimensions as it allows evaluation of existing status of the velopharyngeal and oropharyngeal dimensions under direct visualization, thus allowing a more precise determination of possible detrimental changes that may occur with either maxillary and mandibular setback or advancement.
6.2 REVIEW OF LITERATURE: Orthognathic surgery has been associated with airway narrowing and induction of sleep related breathing disorders. Therefore, the pharyngeal dimensions of 32 orthognathic surgery cases were investigated, and the relationship between the surgery and sleep quality of sleep assessed. The study concluded that a significant decrease retrolingual airway dimensions was found in all patients after mandibular setback surgery and a significant increase in this dimensions after mandibular advancement. 1 A detailed cephalometric analysis was conducted on a sample of 31 adult males who underwent correction of mandibular prognathism by mandibular setback osteotomy (BSRO) with rigid internal fixation to evaluate the changes in uvuloglossopharyngeal morphology, hyoid bone position and head posture. Lateral Cephalogram was obtained 1-3 days prior the operation and at standardized 6 months and 3 years post-operative follow-up. The authors concluded that soft tissue alterations took place as a result of mandibular setback surgery. They comprised positional changes of hyoid bone, increased length and inclination of soft palate, more upright tongue, and reduction of oropharyngeal air way space. Thus all the patients undergoing corrections for mandibular prognathism by setback operations should be carefully evaluated prior to surgery to identify those potentially at risk for development of obstructive sleep apnoea.2
A multidisciplinary approach is essential for examination and diagnosis that helps to determine most appropriate treatment plan for each individual. Hence a reasonable treatment regime is produced, taking consideration of patient’s wishes and overall medical condition. For correction of maxillary and/or mandibular advancement or setback a team of General physician, Anaesthesist, ENT surgeon, Orthodontist and Oral And Maxillofacial surgeon should work together to meet the necessary goals.3
In the present study authors estimated values for pharyngeal airway sagittal dimensions in three levels- naso, oro, and hypopharyngeal – for the young adult patients with class III dentofacial skeletal morphology in comparison with Class I patients with normal dentofacial morphology. Sample size of 32 patients with class III deformity were selected and cephalometric radiographs were taken before and after orthognathic surgery, a paired t test was used to evaluate the difference between class I and Class III pharyngeal airway Sagittal dimensions measurements and statistically analysis revealed a highly significant difference in naso and hypopharyngeal levels. Authors concluded that pre and post operative changes in pharyngeal airway dimensions after bi maxillary surgery showed statistically significant increase in nasopharyngeal airway space, without significant reduction in oro and hypopharyngeal level.4
In this study authors compared speech outcome and velopharyngeal status of 22 subjects with repaired cleft palate who underwent either conventional Lefort I osteotomy or maxillary distraction osteogenesis to correct maxillary hypoplasia. They concluded the study by utilising an assessment protocol involving a variety of outcome measures and careful consideration of reliability factors, which can be a model for further and follow-up studies.5
6.3OBJECTIVES OF STUDY: 1. To evaluate the importance of Nasoendoscope/ Bronchoscope as a diagnostic aid to evaluate the pharyngeal space.
2. To compare Nasoendoscope/ Bronchoscope with Digitalized Lateral Cephalometrics as a diagnostic aid to evaluate pharyngeal dimensions before and after orthognathic surgery.
MATERIALS AND METHODS: 7.1 SOURCE OF DATA: The patients for Orthognathic Surgery will be referred to the Department of Oral & Maxillofacial Surgery by the department of Orthodontia, The Oxford Dental College, Hospital and Research Centre, Bangalore.
7.2 METHOD OF COLLECTION OF THE DATA: The data for Endoscopic evaluation will be obtained from the Department of ENT, St.Johns Medical college and Hospital, Bangalore and The Digitalized Lateral Cephalometrics are obtained from The Department of Oral and Maxillofacial Radiology, The Oxford Dental College & Hospital, Bangalore.
INCLUSION CRITERIA :-
ASA (American Society of Anaesthesiologist) class I and class II.
Patient requiring orthognathic surgery for correcting of skeletal deformity.
Pre and post surgical cephalograms of patients. & Pre and Post surgical nasoendoscopy.
7.3 EQUIPMENT TO BE USED:
Digitalized lateral Cephalogram.
Vista dent software.
7.4 METHODOLOGY: Pre and post operative evaluation of pharyngeal airway dimensions are done using Digitalized Lateral Cephalometric and measurements will be recorded. Now, this is compared with Pre and Post operative measurements taken by Nasoendoscopic Examination.
A comparative study of digitalized lateral cephalometrics over Nasoendoscope/Bronchoscope is also done.
7.5 DOES THE STUDY REQUIRE ANY INVESTIGATION OR INTERVENTION TO BE CONDUCTED ON PATIENTS OR OTHER HUMANS OR ANIMALS? Yes.
7.6 HAS ETHICAL CLEARANCE BEEN OBTAINED FROM YOUR INSTITUTION? Yes.
LIST OF REFERENCES:
Turnbull.N.R, J.M. Battagel. The effect of orthognathic surgery on Pharyngeal Airway Dimensions and Quality of Sleep. J of ortho 2000; 27: 235-47.
Soteris achilleos, Olaf krogstad and Torstein lyberg. Surgical Mandibular Setback and Changes in Uvuloglossopharyngeal Morphology and Head posture.European Ortho society 2000; 22: 383-94.
L’Estrange, J.M.Battagel, P.J. Nolan,B, Harkness & G.I.Jorgensen. The importance Of a multidisciplinary approach to the assessment of patients with obstructive sleep apnoea. J Oral Rehab 1996; 23:72-77.
4. Dace Cakarne, Ilga Urtane, Andrejs Skagers. Pharyngeal airway Sagittal Dimension in Patients with Class III Skeletal Dentofacial Deformity Before and After bimaxillary Surgery
Stomatologija 2003; 5: 13-16.
5. Natthareee chanchareonsook, Tara L. Whitehill, Nabil Samman. Speech outcome and Velopharyngeal Function in Cleft palate: Comparision of Le Fort I Maxillary Osteotomy and Distraction Osteogenesis. Cleft palate- Craniofacial Journal, 2007 Jan; 44(1): 23-32.