Endoscopy evaluation to predict oral appliance outcomes in obstructive sleep apnoea.

The objective of this study was to determine the utility of nasoendoscopy of the upper airway as a predictor of the efficacy of oral appliance treatment in obstructive sleep apnoea (OSA).A total of 61 consecutive patients with moderate-to-severe polysomnographically diagnosed OSA were recruited for this study. Using nasoendoscopy, we prospectively assessed the velopharynx and oro/hypopharynx in each patient while awake and in the supine position. We measured cross-sectional area (CSA), and anteroposterior and lateral diameters of the airway before and after mandibular advancement, and expressed the changes in dimensions as expansion ratios (after/before). We then compared the measurements of responders and nonresponders with oral appliance treatment.The expansion ratio (median (interquartile range)) for the CSA was greater in responders compared with nonresponders in the velopharynx (2.9 (2.3-5.0) versus 1.7 (1.5-1.9), p<0.001) and in the oro/hypopharynx (3.4 (2.5-5.6) versus 2.4 (1.8-3.7), p<0.05). Baseline apnoea-hypopnoea index and the CSA expansion ratio of the velopharynx were independent predictors of oral appliance treatment outcome based on a multivariate logistic regression analysis. The estimated area under the receiver operator characteristic curve was 0.87 and the cut-off value of the expansion ratio was 2.00.These results indicate that nasoendoscopy may have significant clinical utility in predicting the success of oral appliance treatment.

Sleep Stage Coordination of Respiration and Swallowing: A Preliminary Study.

Swallowing is an important physiological response that protects the airway. Although aspiration during sleep may cause aspiration pneumonia, the mechanisms responsible have not yet been elucidated. We evaluated the coordination between respiration and swallowing by infusing water into the pharynx of healthy young adults during each sleep stage. Seven normal subjects participated in the study. During polysomnography recordings, to elicit a swallow we injected distilled water into the pharynx during the awake state and each sleep stage through a nasal catheter. We assessed swallow latency, swallow apnea time, the respiratory phase during a swallow, the number of swallows, and coughing. A total number of 79 swallows were recorded. The median swallow latency was significantly higher in stage 2 (10.05 s) and stage 3 (44.17 s) when compared to awake state (4.99 s). The swallow latency in stage 3 showed a very wide interquartile range. In two subjects, the result was predominantly prolonged compared to the other subjects. There was no significant difference in the swallow apnea time between sleep stages. The presence of inspiration after swallowing, repetitive swallowing, and coughing after swallowing was more frequent during sleep than when awake. This study suggests that the coordination between respiration and swallowing as a defense mechanism against aspiration was impaired during sleep. Our results supported physiologically the fact that healthy adult individuals aspirate pharyngeal secretions during sleep.

Effect of orthodontic treatment on the upper airway volume in adults.

INTRODUCTION: The aim of this study was to examine the effects of orthodontic treatment with and without extractions on the anatomic characteristics of the upper airway in adults. METHODS: For this retrospective study, the pretreatment and posttreatment cone-beam computed tomography scans of 74 adult patients meeting defined eligibility criteria were analyzed. Imaging software was used to segment and measure upper airway regions including the nasopharynx, the retropalatal, and retroglossal areas of the oropharynx, as well as the total airway. The Wilcoxon signed rank test was used to compare volumetric and minimal cross-sectional area changes from pretreatment to posttreatment. RESULTS: The reliability values were high for all measurements, with intraclass correlation coefficients of 0.82 or greater. The volumetric treatment changes for the extraction and nonextraction groups were as follows: total airway, 1039.6 ± 3674.3 mm3 vs 1719.2 ± 4979.2 mm3; nasopharynx, 136.1 ± 1379.3 mm3 vs -36.5 ± 1139.8 mm3; retropalatal, 412.7 ± 3042.5 mm3 vs 399.3 ± 3294.6 mm3; and retroglossal, 412.5 ± 1503.2 mm3 vs 1109.3 ± 2328.6 mm3. The treatment changes in volume or minimal cross-sectional area for all airway regions examined were not significantly (P >0.05) different between the extraction and nonextraction groups. CONCLUSIONS: Orthodontic treatment in adults does not cause clinically significant changes to the volume or the minimally constricted area of the upper airway. These results suggest that dental extractions in conjunction with orthodontic treatment have a negligible effect on the upper airway in adults.

Swallowing and breathing patterns during sleep in patients with obstructive sleep apnea.

PURPOSE: The aims of this study were to determine the frequencies of swallowing and swallowing associated with arousals during sleep in patients with obstructive sleep apnea (OSA) and to determine whether these were associated with the severity of OSA and differed according to the preceding breathing route. METHODS: Standard audio-video polysomnography including an evaluation of swallowing-related elevation of the thyroid cartilage and breathing route (i.e., nasal or oronasal) was undertaken in an academic sleep laboratory. Fifty-six patients were analyzed (13 non-OSA patients, 17 mild, 10 moderate, and 16 severe OSA). RESULTS: The frequency of swallowing per hour of sleep was significantly higher in the severe OSA patients when compared to mild OSA patients (mild OSA, 3.1/h and severe OSA, 8.4/h). This was mainly due to the significantly higher frequency of swallowing associated with a respiratory event-related arousal in the severe OSA patients when compared to non- and mild OSA patients (non-OSA, 0.6/h; mild OSA, 1.0/h; severe OSA, 6.0/h), especially when swallowing was preceded by oronasal breathing (non-OSA, 0.2/h; mild OSA, 0.4/h; severe OSA, 4.2/h). CONCLUSIONS: Swallowing frequency during sleep can increase with increasing OSA severity in most OSA patients. These events are predominately associated with respiratory event-related arousals and are more frequent when preceded by oronasal breathing. The observed swallowing under high ventilatory needs may compromise the maintenance of the pharynx as a conduit for airflow in OSA patients.

A Pilot Study on the Dentoalveolar and Skeletal Effects of Two Functional Appliances in Class II, Division 1 Growing Children.

UNLABELLED: The aim of this preliminary study was to compare the dentoalveolar and skeletal effects of two different Removable Functional Appliances (RFAs) in growing Class II, Division 1 subjects based on pre- and post-treatment cephalometric analyses. Forty subjects with Class II, Division 1 malocclusions were recruited from the undergraduate orthodontic clinic at the University of British Columbia for this clinical trial. All subjects were selected under the same inclusion and exclusion criteria and full orthodontic records were obtained for each subject. They were divided into two groups: 20 (12 males) in RFA-1 group and 20 (14 males) in RFA-2 group. RESULTS: There were no significant differences between the RFA-1 and RFA-2 groups in insertion age (10.4 ± 1.3 years and 10.7 ± 1.4 years, respectively) or treatment duration (163 ± 6.7 months and 16.1 ± 65 months, respectively). There was no significant difference in cephalometric variables between the two groups at baseline. After treatment, both groups demonstrated a statistically significant (P < 0.05) increased SNB and L1-Apo; decreasedANB, Wits, overjet and overbite. CONCLUSIONS: The functional effects of RFA-1 and RFA-2 are comparable in Class II, Division 1 pre-adolescent patients in the same age group. The RFA-1 is effective in generating treatment changes as the suggested wear time was only during sleep.d.

Updates in oral appliance therapy for snoring and obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is increasingly being recognized by the public due to its life-threatening and low curability rate nature. Oral appliances (OAs) were introduced as a treatment option for both non-apneic snoring and OSA to maintain the patency of the upper airway during sleep by repositioning the mandible, tongue, and soft palate. RESULTS: Over the past decade, OAs are enthusiastically studied and concluded as a simple, silent, bed partner-friendly, less invasive, tolerable, and efficacious choice for mild-to-moderate OSA. In the meantime, some challenges remain uncertain such as titration management, 3D image diagnostic tools reliability, and long-term adherence for adult patients. Improvement of temporomandibular joint (TMJ) monitoring and management is recommended, although there is no scientific evidence suggesting consistent undesirable long-term effects of OA on the TMJ. Now that pediatric OSA is being diagnosed more frequently, OA therapy is becoming a promising option for children as well. CONCLUSION: Consistent follow-up and management are needed to increase clinical success rates in OA therapy for OSA. Further educational preparation and support is required for dental and medical professionals to recognize OSA and ensure the best possible patient care.

The relationship between cephalometric carotid artery calcification and Framingham Risk Score profile in patients with obstructive sleep apnea.

PURPOSE: The morbidity rate of arteriosclerosis becomes clinically manifested as acute cardiovascular events. In the progress of atherosclerosis, the carotid artery calcifies and sometimes appears as a calcified mass on a cephalometric radiograph. This study was designed to evaluate cardiovascular risks according to the Framingham Risk Score (FRS) between subjects with and without visible carotid artery calcification on a cephalogram. METHODS: Subjects diagnosed with obstructive sleep apnea (OSA) were divided into two groups according to whether or not calcification was visible on a cephalometric radiograph in the carotid artery area, and the characteristic differences between the two groups were analyzed. The evaluated variables included age, BMI, apnea-hypopnea index (AHI), SpO2, ESS, blood pressure, medication history, diabetes mellitus (DM), drinking, smoking, and lipid-related measurements. FRSs for stroke, general cardiovascular disease (GCD), and coronary heart disease (CHD) were calculated. Statistical analyses were performed (SPSS 18.0) with significance defined as a two-tailed p value less than 0.05. RESULTS: A total of 811 subjects completed the data collection (727 males, age 53.0 ± 12.5 years, AHI 31.7 ± 22.6, times/h). From FRSs, probabilities of a GCD, stroke, and CHD within 10 years were 16.0 ± 9.7, 9.8 ± 6.7, and 11.9 ± 8.3 %, respectively. Some 84 subjects exhibited calcification in the carotid arterial area. Calcification subjects were higher GCD risk and older than subjects who had no identified calcification (20.3 ± 10.1 vs 15.6 ± 20.3 %, p = 0.013, 58.8 ± 11.4 vs. 52.3 ± 12.5 years, p < 0.001). Although there is no significant difference in OSA-related variables and FRSs, subjects with visible calcifications have higher prevalence of high blood pressure medication and DM (p < 0.01). CONCLUSION: While the presence of a calcified mass on a cephalometric radiograph is not diagnostic of atherosclerosis, this information indicates some cardiovascular risk.

Patient preferences and experiences of CPAP and oral appliances for the treatment of obstructive sleep apnea: a qualitative analysis.

OBJECTIVES: The aim of this study is to better understand patients' perspectives and preferences about treatment with continuous positive airway pressure (CPAP) and oral appliance (OA) devices for obstructive sleep apnea. METHODS: The current study used qualitative analysis of four focus group sessions with current CPAP and OA users. Twenty-two participants with OSA who currently use either CPAP or OA participated in the sessions at the University of British Columbia. RESULTS: Five topics from the focus group sessions were descriptively analyzed using NVivo software: goals and expectations of treatment, benefits of treatment for bed partners, side effects and inconveniences of CPAP, side effects and inconveniences of OA, and factors impacting treatment choice. In order of most to least frequently mentioned, patients expressed six expectations of treatment: improved health, apnea elimination, improved sleep, reduced fatigue, reduced snoring, and bed-partner benefits. The most to least mentioned factors impacting treatment choice were device effectiveness, transportability, embarrassment, and cost. CONCLUSIONS: This qualitative study showed that many factors impact patients' experience with their treatment device and that their treatment needs are not only physical but also relate to their lifestyle. This preliminary study provides treatment characteristics and attributes necessary to develop a quantitative questionnaire study, to assist in the selection of therapy, weighing the relative importance of patient and OSA treatment characteristics on treatment preference and adherence. Matching therapy to patient preferences may help identify the most appropriate treatment, and this may achieve greater likelihood of adherence.

Three-dimensional reconstruction of soft palate modeling from subject-specific magnetic resonance imaging data.

PURPOSE: The objectives of this study were to extract a computational three-dimensional (3D) soft palate model from a set of magnetic resonance imaging (MRI) data and to identify an approach that generates a patient-specific model in a computerized visual platform. METHODS: Multiple MRI slices of the head and neck region of a young, non-overweight Caucasian male volunteer were taken in the supine position with a passive oral appliance in place. The DICOM (Digital Imaging and Communications) MRI slices were registered into a high-resolution volumetric data set for manually segmentation to generate a surface mesh and, with additional editing, a volume mesh. For biomechanical dynamic simulation and for physical simulation of the anatomical structures, the volume mesh format and multiple landmarks of each muscle were imported into ArtiSynth, a 3D biomechanical modeling toolkit. RESULTS: The segmented soft palate complex consisted of five groups of muscles: levator veli palatini, tensor veli palatini, palatoglossus, palatopharyngeous and musculus uvulae. The palatine tonsil between the pharyngopalatine and glossopalatine arches was included in the segmentation. CONCLUSIONS: The same procedure was used to build up a generic reference model of the dentition, tongue, mandible and airway from a mixture of medical records (CT and dental casts) of the same subject. This manual segmentation method eliminated the common errors that occur from an automatic segmentation although it was more time-consuming. It remains a fundamental process for analyzing the dynamic interaction between anatomical components in the oral, pharyngeal, and laryngeal areas.

Complete denture wear during sleep in elderly sleep apnea patients--a preliminary study.

OBJECTIVES: There is no consensus in the literature about the impact of complete denture wear on obstructive sleep apnea (OSA). The goal of this randomized clinical study was to assess if complete denture wear during sleep interferes with the quality of sleep. MATERIALS AND METHODS: Elderly edentulous OSA patients from a complete denture clinic were enrolled and received new complete dentures. An objective sleep analysis was determined with polysomnography performed at the sleep laboratory for all patients who slept either with or without their dentures. RESULTS: Twenty-three patients (74% females) completed the study with a mean age of 69.6 years and a mean body mass index of 26.7 kg/m(2). The apnea and hypopnea index (AHI) was significantly higher when patients slept with dentures compared to without (25.9 ± 14.8/h vs. 19.9 ± 10.2/h; p > 0.005). In the mild OSA group, the AHI was significantly higher when patients slept with the dentures (16.6 ± 6.9 vs. 8.9 ± 2.4; p < 0.05), while in moderate to severe OSA patients, the AHI was not significantly different when sleeping with dentures (.30.8 ± 15.6 vs. 25.7 ± 7.5; p = 0.2). The supine AHI in mild patients was related to a higher increase in AHI while wearing dentures (12.7 ± 8.4/h vs. 51.9 ± 28.6/h; p < 0.001). A limitation of the study is that the mild OSA patients had a higher BMI when compared to the moderate to severe OSA patients. Ten out of 14 patients who preferred to sleep with their upper and lower dentures showed an increase in their AHI while wearing dentures to sleep. CONCLUSIONS: Contrary to previous studies, we found that OSA patients may experience more apneic events if they sleep with their dentures in place. Specifically, in mild OSAS patients, the use of dentures substantially increases the AHI especially when in the supine position.

The orthodontist and the obstructive sleep apnea patient.

Obstructive sleep apnea is a common breathing disorder with serious effects on a patient's health and quality of life. Orthodontists should be aware of the disease and competent at recognizing common signs and symptoms in their patients. Due to their expertise and familiarity with growth and development as well as orthopedic and surgical correction of the jaws, orthodontists are ideally suited to treat OSA patients. The goal of this article is to provide an overview to orthodontists on the important role they can play in the treatment of this serious and often under-diagnosed disease.

The correlation between craniofacial morphology and sleep-disordered breathing in children in an undergraduate orthodontic clinic.

PURPOSE: The aim of this study was to assess children in an orthodontic teaching clinic to determine the relationship between sleep-disordered breathing (SDB) symptoms and craniofacial morphology. METHODS: All parents were asked to complete a SDB questionnaire at the commencement of orthodontic therapy. A cephalometric analysis included face heights, hyoid position, soft palate lengths, mandibular, vertical airway, overjet, and overbite. Study model measurements included dental width, depth, and palatal height. The subjects were divided into two groups according to their dentition stage: early or late mixed. RESULTS: Data from 173 children (male 50.3%, mean age 10.1 ± 1.7 years) that completed the OSA-18 questionnaire and the cephalometric (CA) and model (MA) analyses were evaluated. The questionnaire suggested that only two children in the orthodontic pool had an increased chance of exhibiting SDB. However, loud snoring, mouth breathing, and difficulty awakening were reported in more than 20% of the children. Overall, a higher total score correlated with retroclined upper incisors (CA) and high palatal height (MA, p < 0.05). Although there was no significant score differences between the groups, a higher total score correlated with a long soft palate (CA, p < 0.05) in the early mixed dentition group and a high palatal height (MA) in the late mixed dentition group (p < 0.05). CONCLUSION: Even though few patients were suspected as having SDB, symptoms were related to many cephalometric variables and study model measurements. Since the etiology of SDB is believed to involve multiple factors, such patients may exhibit some risk of developing SDB in the future.

Changes in headache characteristics with oral appliance treatment for obstructive sleep apnea.

Changes in headache characteristics in obstructive sleep apnea (OSA) patients following oral appliance treatment was investigated for the first time. Thirteen OSA patients with headaches treated with a mandibular advancement device were investigated. Level I polysomnography and Migraine Disability Assessment Questionnaire were completed before and after treatment. Various headache characteristics and concomitant conditions were analyzed. The patient was considered a headache responder when ≥ 30% reduction in headache frequency following treatment. Differences in headache and polysomnographic parameters were compared between headache responder groups. Eight patients (62%) were headache responders. Eleven patients (85%) before and 7 (54%) after treatment reported morning headaches. Significantly more patients had bilateral headache in the responder group before treatment (P = 0.035). The severest headache intensity (P = 0.018) at baseline showed a significant decrease in the headache responder group after treatment. The time spent in N2 (r = - 0.663, P = 0.014), REM sleep (r = 0.704, P = 0.007) and mean oxygen saturation (r = 0.566, P = 0.044) showed a significant correlation with post-treatment average headache intensity. Pre-treatment lower PLM index (r = - 0.632, P = 0.027) and higher mean oxygen saturation levels (r = 0.592, P = 0.043) were significantly correlated with higher post-treatment severest headache intensity. Treatment with an oral appliance is beneficial for many OSA patients with headaches. It should be considered as an alternative treatment in headache patients with mild to moderate OSA.

Cephalometric calcified carotid artery atheromas in patients with obstructive sleep apnea.

BACKGROUND: In the progress of atherosclerosis, the carotid artery calcifies and sometimes appears as a calcified mass on a cephalometric radiograph. PURPOSE: This study was designed to evaluate the prevalence of calcification in cephalometric radiographs of OSA patients and to identify the differences between subjects with and without carotid artery calcification. METHODS: A total of 1,520 X-rays were evaluated. Data for group A, 508 traditional X-rays, were collected from the UBC Sleep Apnea Dental Clinic and data for group B, 1,012 digital X-rays, were obtained from the Tsuda Hospital in Japan. Subjects were divided into two groups according to whether or not calcification was present in the carotid artery area and the characteristic differences between these two groups were analyzed. DISCUSSION: Group A had 34 (6.7%) subjects who exhibited calcification in the carotid arterial area, while group B had 96 (9.5%) subjects who revealed calcification. Group A calcification subjects had a significantly lower body mass index (BMI) than subjects who had no calcification (26.9 ± 3.2 vs. 29.7 ± 5.6, p<0.01). Group B calcification subjects were older than subjects who had no calcification (57.6 ± 12.6 vs. 49.8 ± 14.5, p<0.000). Previous reports have found the prevalence of calcification on X-rays of OSA patients to be higher than the prevalence of calcification found in the general population. CONCLUSION: While the presence of a calcified mass on a cephalometric radiograph is not diagnostic of atherosclerosis, this information might help to aid in screening for the condition.

Side effects of boil and bite type oral appliance therapy in sleep apnea patients.

INTRODUCTION: Based on a mail-out questionnaire, this study analyzed compliance and side effects of one commonly used (TheraSnore) boil and bite oral appliance (OA) in patients with obstructive sleep apnea. METHODS: The questionnaire was sent to 84 patients 6 months after the delivery of the OA. RESULTS: Fifty-eight percent (n = 47) of the patients returned the questionnaire. There was no significant difference in baseline data [age, body mass index (BMI), apnea-hypopnea index or the Epworth Sleepiness Scale (ESS)] between the returned and nonreturned questionnaires. Of the responding patients, 74.5% (n = 35) continued to use the appliance. Nonusers had a higher BMI and higher baseline ESS when compared with users. The majority (74.3%) of the users and 50.0% of the nonusers previously used a nasal continuous positive airway pressure machine. Some 82.9% of the users wore their OA more than 3 days a week. Of the nonusers, 77.8% stopped using the OA in the first 3 months, and the most frequent reason given was "uncomfortable." Many users complained about a dry mouth and/or excessive salivation and nonusers significantly complained more about ill-fitting appliances. Over 80% of the users experienced improvement in their snoring, daytime sleepiness, and apnea. More than 60% of the users were satisfied with OA therapy. CONCLUSION: While this study demonstrated similar self-reported compliance as previous reports, there were different side effects from those reported for custom-made appliances. Difficulty in optimal fit is considered to be the main cause of the subsequent stopping of the use of the boil and bite appliance.

Evaluation of a portable recording device (ApneaLink) for case selection of obstructive sleep apnea.

OBJECTIVE: This study was designed to assess the sensitivity and specificity of a portable sleep apnea recording device (ApneaLink) using standard polysomnography (PSG) as a reference and to evaluate the possibility of using the ApneaLink as a case selection technique for patients with suspected obstructive sleep apnea (OSA). MATERIALS AND METHODS: Fifty patients (mean age 48.7 +/- 12.6 years, 32 males) were recruited during a 4-week period. A simultaneous recording of both the standard in-laboratory PSG and an ambulatory level 4 sleep monitor (ApneaLink) was performed during an overnight study for each patient. PSG sleep and respiratory events were scored manually according to standard criteria. ApneaLink data were analyzed either with the automated computerized algorithm provided by the manufacturer following the American Academy of Sleep Medicine standards (default setting DFAL) or The University of British Columbia Hospital sleep laboratory standards (alternative setting, ATAL). The ApneaLink respiratory disturbance indices (RDI), PSG apnea-hypopnea indices (AHI), and PSG oxygen desaturation index (ODI) were compared. RESULTS: The mean PSG-AHI was 30.0 +/- 25.8 events per hour. The means of DFAL-RDI and ATAL-RDI were 23.8 +/- 21.9 events per hour and 29.5 +/- 22.2 events per hour, respectively. Intraclass correlation coefficients were 0.958 between PSG-AHI and DFAL-RDI and 0.966 between PSG-AHI and ATAL-RDI. Receiver operator characteristic curves were constructed using a variety of PSG-AHI cutoff values (5, 10, 15, 20, and 30 events per hour). Optimal combinations of sensitivity and specificity for the various cutoffs were 97.7/66.7, 95.0/90.0, 87.5/88.9, 88.0/88.0, and 88.2/93.9, respectively for the default setting. The ApneaLink demonstrated the best agreement with laboratory PSG data at cutoffs of AHI >or= 10. There were no significant differences among PSG-AHI, DFAL-RDI, and ATAL-RDI when all subjects were considered as one group. ODI at 2%, 3%, and 4% desaturation levels showed significant differences (p < 0.05) compared with PSG-AHI, DFAL-RDI, and ATAL-RDI for the entire group. CONCLUSION: The ApneaLink is an ambulatory sleep monitor that can detect OSA and/or hypopnea with acceptable reliability. The screening and diagnostic capability needs to be verified by further evaluation and manual scoring of the ApneaLink. It could be a better choice than traditional oximetry in terms of recording respiratory events, although severity may be under- or overestimated.

Effect of 2 jaw exercises on occlusal function in patients with obstructive sleep apnea during oral appliance therapy: a randomized controlled trial.

INTRODUCTION: The aim of this study was to compare the effects on objective occlusal function of 2 types of jaw exercises during oral appliance therapy in patients with obstructive sleep apnea (OSA). METHODS: Sixteen consecutive subjects with snoring or OSA undergoing oral appliance therapy were included in this study; the results were based on 10 patients who completed it. The patients were randomized to start with either a jig exercise or stretching movements for 1 month; after 1 month without exercise, they crossed over to the other exercise for 1 month. An occlusal diagnostic system that consisted of a pressure-sensitive sheet and an image scanner was used to evaluate occlusal contact area and bite force. RESULTS: Both exercises produced significant increases in occlusal contact area and bite force in the morning compared with the period of no exercise. At night, the molar region had significant improvements in occlusal contact area and bite force only during stretching movements. We found no significant differences between the 2 exercises, but stretching movements tended to be more effective in the molar region, whereas the jig exercise tended to be more effective in the anterior region. CONCLUSIONS: Jaw exercises might help relieve masticatory muscle stiffness and accelerate the repositioning of the mandible to the normal position, in addition to inhibiting or minimizing the occlusal functional changes in predisposed patients.

Stability of maxillary expansion and tongue posture.

OBJECTIVE: To evaluate the adaptive changes and the stability in tongue posture following rapid maxillary expansion (RME) in patients without any signs or symptoms of respiratory disturbances. MATERIALS AND METHODS: Growing subjects with maxillary constrictions and bilateral buccal crossbites were included in the treatment group (n = 20). A control group (n = 20) comprised subjects with normal dentoskeletal features. RME appliances were used in the treatment group, with an average active expansion of 15 +/- 2 days. Cephalometric radiographs were traced and digitized to evaluate static tongue posture before RME and 6.75 +/- 0.48 months after RME. Follow-up radiographic evaluations of 17 expansion cases were also performed after an average of 29.25 +/- 1.85 months. Independent and paired t-tests were conducted to evaluate changes in tongue posture within and between groups. RESULTS: Results revealed significant reductions of tongue-to-palate (P < .05) as well as hyoid bone-to-mandibular plane (P < .01) distances following RME. The new tongue posture was found to be stable during the follow-up period. CONCLUSIONS: A higher tongue posture can be obtained with RME in children with no reported respiratory disturbances.

Three-dimensional computer-assisted study model analysis of long-term oral-appliance wear. Part 1: Methodology.

INTRODUCTION: The aim of this study was to test a 3-dimensional (3D) computer-assisted dental model analysis system that uses selected landmarks to describe tooth movement during treatment with an oral appliance. METHODS: Dental casts of 70 patients diagnosed with obstructive sleep apnea and treated with oral appliances for a mean time of 7 years 4 months were evaluated with a 3D digitizer (MicroScribe-3DX, Immersion, San Jose, Calif) compatible with the Rhinoceros modeling program (version 3.0 SR3c, Robert McNeel & Associates, Seattle, Wash). A total of 86 landmarks on each model were digitized, and 156 variables were calculated as either the linear distance between points or the distance from points to reference planes. Four study models for each patient (maxillary baseline, mandibular baseline, maxillary follow-up, and mandibular follow-up) were superimposed on 2 sets of reference points: 3 points on the palatal rugae for maxillary model superimposition, and 3 occlusal contact points for the same set of maxillary and mandibular model superimpositions. The patients were divided into 3 evaluation groups by 5 orthodontists based on the changes between baseline and follow-up study models. RESULTS: Digital dental measurements could be analyzed, including arch width, arch length, curve of Spee, overbite, overjet, and the anteroposterior relationship between the maxillary and mandibular arches. A method error within 0.23 mm in 14 selected variables was found for the 3D system. The statistical differences in the 3 evaluation groups verified the division criteria determined by the orthodontists. CONCLUSIONS: The system provides a method to record 3D measurements of study models that permits computer visualization of tooth position and movement from various perspectives.

Three-dimensional computer-assisted study model analysis of long-term oral-appliance wear. Part 2. Side effects of oral appliances in obstructive sleep apnea patients.

INTRODUCTION: Oral appliances (OAs) are widely prescribed for the treatment of obstructive sleep apnea (OSA). The occlusal changes that occur after long term OA treatment have not been well described based on detailed computerized three-dimensional (3D) assessment. METHODS: Seventy patients with OSA (mean age, 50.0 years) who had been treated with an OA were identified for this study. A MicroScribe-3DX dental study model analysis system was used to make 3D measurements on baseline and follow-up (88.4 +/- 26.7 months) study models. RESULTS: The following dental measurements showed significant changes (P <0.05) with long-term use of an OA: mandibular arch width increased more than maxillary arch width, crowding decreased in both arches, the curve of Spee became flat in the premolar area, the mandibular canine to second molar segment moved forward in relation to the maxillary arch, the bite opened and the overjet decreased except in some molar areas. CONCLUSIONS: A variety of occlusal changes occur with long-term OA treatment for OSA. The changes could be regarded as either adverse or beneficial depending upon the baseline characteristics.