ABSTRACT
Bilateral sagittal split osteotomy (BSSO) is an effective and commonly used treatment to correct mandibular hypo- and hyperplasia. Hypoesthesia of the inferior alveolar nerve (IAN) is a common complication of this surgical procedure. This prospective multi-centre study aimed to determine the incidence of neurosensory disturbances of the IAN after BSSO procedures performed without the use of chisels. Our study group comprised 158 patients, with a follow-up period of 1 year, who underwent BSSO (with or without Le Fort I) that incorporated the use of sagittal split separators and splitters but no chisels. The percentage of BSSO split procedures that resulted in IAN damage was 5.1%. The percentage of patients (without genioplasty) who experienced IAN damage was 8.9%. The concomitant genioplasty in combination with BSSO was significantly associated with hypoesthesia. Peri-operative removal of the wisdom tooth or a Le Fort I procedure did not influence post-operative hypoesthesia. We believe that the use of splitting forceps and elevators without chisels leads to a lower incidence of persistent post-operative hypoesthesia 1 year after BSSO of the mandible, without increasing the risk of a bad split.
Subject(s)
Cranial Nerve Diseases/etiology , Hypesthesia/etiology , Mandible/surgery , Mandibular Nerve/physiopathology , Osteotomy, Sagittal Split Ramus/adverse effects , Adolescent , Adult , Age Factors , Bone Screws , Cheek/innervation , Chin/surgery , Female , Follow-Up Studies , Forehead/innervation , Humans , Lip/innervation , Male , Mandible/innervation , Mandibular Advancement/adverse effects , Mandibular Advancement/instrumentation , Middle Aged , Molar, Third/surgery , Osteotomy, Le Fort/methods , Osteotomy, Sagittal Split Ramus/instrumentation , Prospective Studies , Tooth Extraction/methods , Touch/physiology , Trigeminal Nerve Injuries/etiology , Young AdultABSTRACT
OBJECTIVE: Surgical mandibular advancement procedures induce major adaptations of jaw-closing muscles. In this study, adaptation of antagonist muscles, the lateral pterygoid (LPM) and anterior digastric (DigA) muscles, was evaluated. STUDY DESIGN: Eighteen adult patients with mandibular retrognathia and individually varying vertical craniofacial dimensions were treated with bilateral sagittal split osteotomies (BSSO), in some cases combined with a Le Fort I osteotomy (LF Bimax). The sample was divided into 1 short-face (SF, n = 7) and 2 long-face groups (LF BSSO, n = 3; and LF Bimax, n = 8). Pre- and postoperative maximum cross-sectional areas (CSA) and volumes were compared in these groups. RESULTS: Postoperatively, CSA and volume of LPM increased in BSSO cases and decreased in bimaxillary cases. Inconsistent increases and decreases of CSA and volume of DigA were seen in all groups. CONCLUSIONS: The LPM became larger in SF and LF BSSO patients and smaller in LF Bimax patients. The DigA adapted unpredictably.
Subject(s)
Face/anatomy & histology , Mandible/surgery , Mandibular Advancement/methods , Neck Muscles/physiology , Pterygoid Muscles/physiology , Adaptation, Physiological , Adolescent , Adult , Cephalometry , Cluster Analysis , Female , Humans , Linear Models , Magnetic Resonance Imaging , Male , Maxillofacial Development , Middle Aged , Neck Muscles/anatomy & histology , Pterygoid Muscles/anatomy & histology , Retrognathia/surgery , Vertical DimensionABSTRACT
OBJECTIVE: Surgical mandibular advancement influences the biomechanics of the mandible and as a result may provoke relapse. In this study, the adaptation of the masseter (MAS) and medial pterygoid muscles (MPM) after surgical mandibular advancement was evaluated. STUDY DESIGN: Of 12 patients with mandibular retrognathia and varying vertical craniofacial morphology, axial and 30 degrees angulated magnetic resonance imaging (MRI) scan series were taken preoperatively and 10 to 48 months postoperatively. Using cluster analysis, subjects were assigned to a long-face (LF) and a short-face (SF) cluster. Subsequently, preoperative and postoperative maximum cross-sectional areas and volumes of the MAS and MPM were compared in these groups. RESULTS: The cross-sectional area and volume of the MAS decreased significantly in both the SF and LF cluster (up to 18%). Although not significantly, this phenomenon tended to be more pronounced in LF patients. The cross-sectional area of the MPM showed less adaptation. CONCLUSION: The jaw-closing muscles become significantly smaller after surgical mandibular advancement, irrespective of the vertical craniofacial type.
