Sila Mermut Gokce

Changes in posterior airway space, pulmonary function and sleep quality, following bimaxillary orthognathic surgery

Bimaxillary orthognathic surgery (BOS) is commonly used in the correction of severe Class III deformities (mandibular prognathism with maxillary retrognathism). The postural response of the pharyngeal airway after mandibular setback and maxillary advancement procedures is clinically crucial for maintaining optimum respiration. Patients might suffer from obstructive sleep apnoea, postoperatively. The aim of this study was to determine the effects of BOS on pharyngeal airway space, respiratory function during sleep and pulmonary functions. 21 male patients were analysed using cephalometry, spirometry for pulmonary function tests, and a 1 night sleep study for full polysomnography before and 17±5 months after BOS. The data show that the hyoid bone repositioned to the inferior, the tongue and soft palate displaced to the posterior, narrowed at the oropharynx and hypopharynx and widened at the nasopharynx and velopharynx levels significantly (p<0.05). The alterations indicated decreased airway resistance and better airflow. As a consequence of polysomnography evaluation, the sleep quality and efficiency of the patients improved significantly after BOS. Patients who undergo BOS should be monitored with pulmonary function tests and polysomnography pre- and postoperatively to detect any airway obstruction.

Nasal cavity volume changes after rapid maxillary expansion in adolescents evaluated with 3-dimensional simulation and modeling programs

INTRODUCTION The purpose of this study was to evaluate the effects of rapid maxillary expansion on nasal cavity volume by using 3-dimensional simulation and modeling programs. METHODS The study group consisted of 15 patients (9 boys, 6 girls; mean age, 13.86 years) with maxillary constriction. Computed tomography scans were obtained before treatment and 6 months after the end of expansion. All computed tomography data were transferred to a computer, and the nasal cavity and maxillary teeth were segmented by using the Mimics and Simplant Ortho software programs (both, Materialise, Leuven, Belgium). Paired samples t tests were used to compare pretreatment and posttreatment nasal cavity volumes and maxillary areas. Data analysis was performed by using the software program SPSS for Windows (version 15.00; SPSS, Chicago, Ill). RESULTS Rapid maxillary expansion treatment induced significant increases in nasal cavity volume (P ≤ 0.001) and maxillary transverse dimensions (P ≤ 0.001). CONCLUSIONS Both anterior-to-posterior and coronal-to-cranial expansions were observed after rapid maxillary expansion treatment, with the direction of expansion most likely affected by resistance from the cranial bones.

Effects of hyperbaric oxygen during experimental tooth movement.

OBJECTIVE To determine the effects of hyperbaric oxygen (HBO) on bone remodeling during orthodontic tooth movement. MATERIALS AND METHODS Twenty-four male, adult Sprague Dawley rats were randomly divided into two groups. HBO was administered in the first group, and the second group served as a control. The mandibular first molars were moved mesially by means of Ni-Ti closed coil springs in all groups. RESULTS Results were evaluated histomorphometrically and the parameters of trabecular bone volume (BV/TV), trabecular bone number (Tr.N), and trabecular separation (Tr.Sep) were evaluated at the interradicular bone area of the mandibular first molars. Increases in BV/TV and Tr.N and decreases in Tr.Sep revealed the osteoblastic activity of HBO. HBO application caused an increase in bone apposition and osteoblastic activity or a decrease in osteoclastic activity. CONCLUSIONS HBO enhanced the bone formation during experimental tooth movement. Therefore, the findings of this study support our hypothesis that osteoblastic activity might be modulated by changes in the environmental oxygen tension.

Evaluation of hyoid bone movements in subjects with open bite: a study with real-time balanced turbo field echo cine-magnetic resonance imaging

Objective To assess the position and movements of the hyoid bone during deglutition in patients with open bite. Methods Thirty-six subjects were divided into 2 groups according to the presence of anterior open bite. The open bite group (OBG) and control group each comprised 18 patients with a mean overbite of -4.9 ± 1.9 mm and 1.9 ± 0.7 mm. The position of the hyoid bone during the 4 stages of deglutition was evaluated by measuring vertical and horizontal movement of the bone. Results Interactions of group and stage showed no significant effect on the measurements (p > 0.05). However, when group and stage were evaluated individually, they showed significant effects on the measurements (p < 0.001). In OBG, the hyoid bone was more inferiorly and posteriorly positioned, and this position continued during the deglutition stages. Conclusions The hyoid bone reaches the maximum anterior position at the oral stage and maximum superior position at the pharyngeal stage during deglutition. Open bite does not change the displacement pattern of the bone during deglutition. The hyoid bone is positioned more inferiorly and posteriorly in patients with open bite because of released tension on the suprahyoid muscles.

Three-dimensional evaluation of nasal and pharyngeal airway after Le Fort I maxillary distraction osteogenesis.

The aims of this study were to evaluate volumetric changes in the nasal cavity (NC) and pharyngeal airway space (PAS) after Le Fort I maxillary distraction osteogenesis (MDO) using a three-dimensional (3D) simulation program, and to determine the effects of MDO on respiratory function during sleep with polysomnography (PSG). 3D computed tomography images were obtained and analyzed before surgery (T0) and at a mean 8.2 ± 1.2 months postsurgery (T1) (SimPlant-OMS software) for 11 male patients (mean age 25.3 ± 5.9 years) with severe skeletal class III anomalies related to maxillary retrognathia. The simulation of osteotomies and placement of distractors were performed on stereolithographic 3D models. NC and PAS were segmented separately on these models for comparison of changes between T0 and T1. PSG including the apnoea-hypopnoea index (AHI), sleep efficiency, sleep stages (weakness, stages 1-4, and rapid eye movement (REM)), and mean lowest arterial O2 saturation were obtained at T0 and T1 to investigate changes in respiratory function during sleep. MDO was successful in all cases as planned on the models; the average forward movement at A point was 10.2mm. Increases in NC and PAS volume after MDO were statistically significant. These increases resulted in significant improvement in sleep quality. PSG parameters changed after MDO; AHI and sleep stages weakness, 1, and 2 decreased, whereas REM, stages 3 and 4, sleep efficiency, and mean O2 saturation increased.

Relationship between Class III malocclusion and hyoid bone displacement during swallowing: a cine-magnetic resonance imaging study

Objective The displacement of the hyoid bone (HB) is a critical biomechanical component of the swallowing function. The aim of this study was to evaluate the swallowing-induced vertical and horizontal displacements of the HB in subjects with 2 different magnitudes of skeletal Class III malocclusion, by means of real-time, balanced turbo-field-echo (B-TFE) cine-magnetic resonance imaging. Methods The study population comprised 19 patients with mild skeletal Class III malocclusion, 16 with severe skeletal Class III malocclusion, and 20 with a skeletal Class I relationship. Before the commencement of the study, all subjects underwent cephalometric analysis to identify the nature of skeletal malformations. B-TFE images were obtained for the 4 consecutive stages of deglutition as each patient swallowed 10 mL of water, and the vertical and horizontal displacements of the HB were measured at each stage. Results At all stages of swallowing, the vertical position of the HB in the severe Class III malocclusion group was significantly lower than those in the mild Class III and Class I malocclusion groups. Similarly, the horizontal displacement of the HB was found to be significantly associated with the severity of malocclusion, i.e., the degree of Class III malocclusion, while the amount of anterior displacement of the HB decreased with an increase in the severity of the Class III deformity. Conclusions Our findings indicate the existence of a relationship between the magnitude of Class III malocclusion and HB displacement during swallowing.

The effect of human amniotic fluid on mandibular distraction osteogenesis

The aim of this study was to evaluate the effects of local administration of human amniotic fluid (HAF) on newly formed bone obtained by mandibular distraction osteogenesis (DO) with histomorphometry. A unilateral mandibular osteotomy at the left corpus was performed in 32 adult male rabbits. After a 5-day latency period, the left mandibles were lengthened by mandibular DO over 5 days, at a rate of 1mm/day, via a custom-made distractor. After the distraction, the rabbits were divided randomly into four groups: 0.3 ml HAF was injected into the distraction gap followed by 21 (group 1) or 45 (group 2) days of consolidation; or 0.3 ml normal saline (NS) was administered followed by 21 (group 3) or 45 (group 4) days of consolidation. Mandibles were removed at the end of the consolidation period and investigated histomorphometrically. The newly formed bone area (NFBA) and number of fibroblasts increased significantly in the HAF groups compared to the NS groups (NFBA: group 1 vs. group 3, P<0.05; group 2 vs. group 4, P<0.01; fibroblasts: group 1 vs. group 3, and group 2 vs. group 4, P<0.05), and also in both 45-day consolidation groups compared to the 21-day consolidation groups (NFBA: group 1 vs. group 2, and group 3 vs. group 4, P<0.001; fibroblasts: group 1 vs. group 2, and group 3 vs. group 4, P<0.01). Additionally, the numbers of osteoblasts and capillaries were increased significantly at 45 days of consolidation compared to 21 days in both the HAF and NS groups (osteoblasts: group 1 vs. group 2, P<0.01; group 3 vs. group 4, P<0.05; capillaries: group 1 vs. group 2, and group 3 vs. group 4, P<0.01). Histomorphometric analysis demonstrated that local HAF administration effectively accelerated bone formation. Thus, a HAF injection procedure could improve new bone formation around the bone in maxillofacial operations such as DO.

Definition of pharyngeal airway, tongue dimensions and hyoid position in healthy subjects -

The purposes of this study were to establish the normative data for the upper airway dimensions and tongue size; hyoid position and to evaluate the cervico-craniofacial skeletal morphology of the anatomical differences between sexes in healthy subjects. The upper airways of 50 male and 53 female healthy volunteers were retrospectively evaluated by lateral skull radiographs. Anatomical pharyngeal linear measurements and craniocervical postural relationships were analyzed. To set-up the reference values for cervico-craniofacial skeletal morphology of the healthy subjects, the craniovertical, craniocervical, cervicohorizontal postural relationships and the curvature of the cervical column were also analyzed. Cephalometric measurments of healthy male individuals showed statistically greater values in all sagittal pharyngeal structural dimensions when compared with healthy female subjects, with the exception of the craniocervical angulations related to head posture.