Optimal placement of bipolar surface EMG electrodes in the face based on single motor unit analysis.

Locations of surface electromyography (sEMG) electrodes in the face are usually chosen on a macro-anatomical basis. In this study we describe optimal placement of bipolar electrodes based on a novel method and present results for lower facial muscles. We performed high-density sEMG recordings in 13 healthy participants. Raw sEMG signals were decomposed into motor unit action potentials (MUAPs). We positioned virtual electrode pairs in the interpolated monopolar MUAPs at different positions along muscle fiber direction and calculated the bipolar potentials. Electrode sites were determined where maximal bipolar amplitude was achieved and were validated. Objective guidelines for sEMG electrode placement improve the signal-to-noise ratio and may contribute to reduce cross talk, which is particularly important in the face. The method may be regarded as an important basis for improving the validity and reproducibility of sEMG in complex muscle areas.

A randomized prospective long-term study of two oral appliances for sleep apnoea treatment.

Various types of mandibular protrusive appliances have revealed different treatment success in mild-to-moderate obstructive sleep apnoea (OSA). The present study compared the long-term effect of two different appliances in the treatment of OSA. A total of 103 patients with OSA were randomized and treated with an IST((R)) or Thornton Anterior Positioner (TAP()) appliance. They were followed-up after a short-term treatment period of 6 months and long-term treatment period of over 24 months. Sleep studies in the sleep laboratory were conducted with and without the appliances, and various questionnaires assessing subjective daytime sleepiness, sleep quality, quality of life and symptom scores were administered at each time interval. Quality of life, sleep quality, sleepiness, symptoms and sleep outcome showed significant improvement in the short-term evaluation with both appliances, but the TAP() appliance revealed a significantly greater effect. After more than 2 years of treatment, sleep outcomes revealed an equal effect with both appliances. The subjective benefits achieved initially lessened significantly. This study illustrates that both the IST((R)) and the TAP() appliances are effective therapeutic devices for OSA after a period of over 24 months. Lack of compliance may be due to insufficient improvement in anticipated subjective symptoms and/or a recurrence of symptoms over time.

Dental side effects of mandibular advancement appliances - a 2-year follow-up.

BACKGROUND AND OBJECTIVES: Mandibular advancement appliances are employed in treating snoring and various forms of obstructive sleep apnea syndrome (OSAS). The splints facilitate the displacement of the mandible anteriorly and widens the pharyngeal lumen during sleep. Two-splint systems are anchored on the dental arches in the maxilla and mandible. The resulting reciprocal forces are transferred onto the teeth, leading to dental side effects when used long-term. We retrospectively examined the dental changes that occurred after patients had worn the Thornton Adjustable Positioner (TAP) for over two years. PATIENTS AND METHODS: We enrolled all patients consecutively in whom the diagnosis of OSAS was made following polysomnography in a sleep laboratory between January 2004 and December 2005 and who had been treated primarily with a TAP. We compared the patients' baseline findings with follow-up findings after more than 24 months of continuous appliance wear. RESULTS: 24/47 of the patients were still wearing the splints regularly after an average of 33 +/- 9.1 months. Overbite was highly significantly reduced (p = 0.006). We noted a reduction in the frontal overbite of more than 1 mm in ten patients (47.6%), and the overbite of one patient decreased by 4 mm. The maxillary front teeth showed significant palatal tipping and those in the mandible significant labial tipping. CONCLUSIONS: Clinically small but statistically significant dental side effects predominantly affecting the incisors' inclination occur after long-term wear of a TAP appliance. The clinical relevance of these dental changes to the patient can only be judged individually within the scope of an entire assessment.

Dentofacial parameters explaining variability in retroclination of the maxillary central incisors.

BACKGROUND AND AIM: The interrelation between retroclination of the maxillary central incisors and dentofacial parameters is a controversial subject in the literature. In contrast to comparisons between malocclusion and control groups, the objective of the present study was to identify skeletal, dentoalveolar or perioral (soft-tissue) factors which primarily determine how severely retroclination is individually manifested. MATERIALS AND METHODS: For this purpose we evaluated the pretherapeutic lateral cephalograms of 83 patients with an inclination of the maxillary central incisors ranging from physiological values to very severe retroclination (inclination to anterior cranial base between 104 degrees and 64 degrees ). A detailed analysis of the skeletal, dentoalveolar, and soft-tissue morphology was performed using lateral cephalograms taken prior to therapy. The statistical analysis included the calculation of multiple regression models for maxillary central incisor inclination and different parameters describing the lip-to-incisor relationship as dependent variables. RESULTS: A regression model including 1) the lip-line level measured at the dorsal upper-lower lip contact point, 2) the sagittal intermaxillary relationship, and 3) the inclination of the mandibular central incisors explained 81% of the variability in maxillary central incisor inclination (p < 0.0001 for all three parameters). Statistical analysis of the morphologic base of a high dorsal lip-line level (i.e., the predominant characteristic in the retroclination cases) revealed the significance of soft-tissue, dentoalveolar, and skeletal variables (p < 0.001). CONCLUSIONS: Complementary to results of previous resting lippressure measurements, this cephalometric study suggests that a high lip-line level is the predominant causative factor for a cover- bite or Class II, Division 2 malocclusion. Therefore, we conclude that (1) lip-line measurements should be included in routine cephalometric diagnostics, and (2) that a high lip-line must be eliminated by therapeutic measures in these malocclusions to prevent a post-orthodontic relapse.

Long-term stability of unilateral posterior crossbite correction.

OBJECTIVE: To evaluate the stability of orthodontically corrected unilateral posterior crossbite in patients treated either by rapid maxillary expansion or with slow expansion devices in the early (mean age 7.2 years, n = 50) or late mixed dentition (mean age 9.9 years, n = 50). MATERIALS AND METHODS: The observation periods were approximately 8 years for the early treatment groups and 6.5 years for the late treatment groups. The measurements were made on plaster casts at the following time points: before treatment (T1), after crossbite correction (T2), at the end of active orthodontic treatment (T3), and about 2 years after the end of active treatment (T4). Midline deviation and the skeletal classification of the malocclusion were also evaluated. RESULTS: Almost 80% of the treated patients showed long-term stability of the corrected unilateral posterior crossbite. More than 70% of the patients were treated for the mandibular midline deviation. At the end of active treatment, 50% of the patients showed a skeletal Class III craniofacial morphology. CONCLUSIONS: The results emphasize that determination of the correct treatment approach for the individual patient is the basic principle underlying the therapeutic success in unilateral crossbite cases. In patients where a broad lower arch is a cofactor in the etiology of the lateral crossbite, the treatment approach should be focused on both arches and not be limited to the constricted upper arch.

One- or two-stage palate closure in patients with unilateral cleft lip and palate: comparing cephalometric and occlusal outcomes.

OBJECTIVE: To assess facial growth and dentoalveolar development in two groups of patients with complete unilateral cleft lip and palate. Primary surgical treatment differed in the timing of hard palate closure. DESIGN: Forty-three patients with unilateral cleft lip and palate were examined. Twenty-two patients underwent early one-stage closure of the hard and soft palate cleft (mean age 23.0 +/- 4.7 months); in 21 patients, the hard palate closure was delayed to 86.3 +/- 39.2 months of age. Lateral cephalograms and dental casts were consecutively analyzed at four stages between 6 and 18 years of age. RESULTS: Lateral cephalometric analysis revealed no significant intergroup differences in the sagittal and vertical craniofacial dimensions at any time. Dental cast analysis showed constriction of the upper anterior arch width at the ages of 6 and 10 years in patients with one-stage surgical palate closure, but a difference could no longer be verified at the ages of 15 and 18 years. CONCLUSIONS: The transverse distances in the upper jaw developed initially more positively in the group with delayed hard palate closure, but it became apparent later that the transverse deficiency after one-stage palate closure could be compensated for. When considering surgical treatment in general, the advantages of the delayed hard palate closure must be weighed against criteria favoring the early one-stage closure of the hard and soft palate.

Lip-to-incisor relationship and postorthodontic long-term stability of cover-bite treatment.

OBJECTIVE: To investigate the impact of a persisting high lip line and other potential relapse-inducing factors on long-term stability of orthodontic correction of retroinclined maxillary central incisors. MATERIALS AND METHODS: Thirty-one cover-bite ("Deckbiss") patients with retroinclined maxillary central incisors and a deep frontal overbite were evaluated. The maxillary central incisor inclination was determined odontometrically with study models made pretreatment, posttreatment, and at a follow-up examination (mean posttherapeutic interval: 9.0 years). The lip-to-incisor relationship, the interincisal angle, and the anteroposterior maxillary central incisor position were measured on lateral cephalograms taken after active treatment. RESULTS: The relapse tendency of the orthodontic correction of the retroinclined maxillary central incisors displayed great interindividual variability with a range of posttherapeutic inclination change of -6.75 degrees to +8.00 degrees. Multiple regression analysis revealed an increased tendency for relapse in patients with (1) a high posttherapeutic (dorsal) lip line level combined with the maxillary central incisor and lower lip contact only in the incisal crown area (P < .01) and (2) a marked therapeutically induced inclination change of the maxillary central incisors (P < .05). Interrelations between the relapse of the corrected maxillary central incisors and other evaluated parameters were not statistically significant. CONCLUSIONS: For maximum treatment stability, the elimination of an excessive overlap of the upper incisors by the lower lip should be regarded as one of the most important therapeutic objectives when treating this malocclusion.

Topographical characteristics of motor units of the lower facial musculature revealed by means of high-density surface EMG.

The objective of this study was to systematically characterize motor units (MUs) of the musculature of the lower face. MU endplate positions and principal muscle fiber orientations relative to facial landmarks were identified. This was done by the analysis of motor unit action potentials (MUAPs) in the surface electromyogram. Thirteen specially trained, healthy subjects performed selective contractions of the depressor anguli oris, depressor labii inferioris, mentalis, and orbicularis oris inferior muscles. Signals were recorded using recently developed, 0.3-mm thin and flexible high-density surface electromyography (sEMG) grids (120 channels). For each subject and each muscle and for different low contraction levels, representative MUAPs ("MU fingerprints") were extracted from the raw sEMG data according to their spatiotemporal amplitude characteristics. We then topographically characterized the lower facial MUs' endplate zones and main muscle fiber orientations on the individual faces of the subjects. These topographical MU parameters were spatially warped to correct for the different sizes and shapes of the faces of individual subjects. This electrophysiological study revealed a distribution of the lower facial MU endplates in more or less restricted, distinct clusters on the muscle often with eccentric locations. The results add substantially to the basic neurophysiologic and anatomical knowledge of the complex facial muscle system. They can also be used to establish objective guidelines for placement of conventional (surface or needle) EMG electrodes as well as for clinical investigations on neuromuscular diseases affecting the facial musculature. The localized endplate positions may also indicate optimal locations for botulinum toxin injection in the face.

A retrospective cephalometric study for the quantitative assessment of relapse factors in cover-bite treatment.

BACKGROUND AND AIM: Cover-bite ("Deckbiss") is regarded as a highly relapse-prone malocclusion. In this context the great significance of a high lip line (LipL) as an etiologic factor for the retroclination of the upper central incisors was recently proven within the framework of lip pressure measurements. It therefore seemed likely that a persisting high LipL after correction of cover-bite might have an equally negative impact on the stability of the treatment outcome. MATERIALS AND METHODS: This issue was investigated in the present retrospective study by cephalometric analysis of the findings prior to therapy (T1), immediately after active mechanotherapy (T2), and after a mean follow-up period of 2 years (T3). The study group consisted of 40 former cover-bite patients with initial linguoversion of the upper central incisors (axial angle to anterior cranial base < 98 degrees ) and anterior deep bite (> or = 4 mm) from the records of the Department of Orthodontics, University of Freiburg i. Br., Germany. RESULTS AND CONCLUSIONS: The average relapse was ca. 20% of the total correction of the anterior linguoversion and deep bite, with the relapse tendency, however, displaying substantial interindividual variations. Multiple regression analysis revealed an increased relapse tendency in specific cases: patients with maxillary extractions, cases with a pronounced therapeutically induced change of upper central incisor inclination, and patients with a high post-therapeutic LipL or with poor compliance in the retention phase. In view of the relatively good opportunity to influence the level of the LipL therapeutically, one of the most important therapeutic objectives for cover-bite patients should be to reduce the amount by which the lower lip overlaps the upper incisors ( to a maximum value of 3 mm). This can be achieved by active mechanical intrusion of the upper incisors. If the orthodontist fails to take account of this aspect when planning or performing the treatment, he has to accept an increased risk of relapse.

Case control study in the treatment of obstructive sleep-disordered breathing with an intraoral protrusive appliance.

BACKGROUND: Mandibular protrusive appliances have long been used to treat obstructive sleep apnea/hypopnea syndrome (OSAHS). Their efficacy regarding respiration during sleep varies greatly and remains difficult to predict. In this study the efficacy of a two-splint appliance on nocturnal breathing disorders, sleep profile, and daytime sleepiness were evaluated according to a specially-designed treatment process. PATIENTS AND METHODS: In this study 42 consecutive OSAHS patients who had been fitted with a mandibular protrusive appliance according to a preset treatment regimen were included in a follow-up analysis. The diagnosis and the degree of severity of OSHAS were determined by polysomnography in the sleep laboratory. The treatment regimen was established with the sleep laboratory physician. Treatment regimen included the diagnostic procedure in the sleep laboratory, each patient's dental requirements, the fabrication of the appliance used, and the titration of the mandibular protrusion. After having grown accustomed to the appliance for 24.5 +/- 7.8 days, 34 patients underwent overnight polysomnography. RESULTS: The mean apnea/hypopnea index decreased significantly from 19.6 +/- 12.8 to 3.3 +/- 7.8 events per hour to 83%; the apnea index also improved significantly, as did minimal oxygen saturation and the desaturation index. Changes in sleep profile did not reach statistical significance; the arousal index (p < 0.02) and the subjectively-assessed daytime sleepiness (p < 0.02) decreased significantly. A therapeutically-required AHI of below 5 events per hour was achieved in 88.2% of the patients. CONCLUSION: A significant improvement in the respiratory situation of the vast majority of OSAHS patients, particularly in their AHI, can be achieved when one applies the procedural steps and employs the mandibular protrusive appliance we describe herein.

Cephalometric assessment of the posterior airway space in patients with cleft palate after palatoplasty.

OBJECTIVE: Upper airway obstruction and mouth breathing influence facial growth and development, which may result in breathing disorders while asleep. The purpose of the present investigation was to analyze cephalometric alterations between patients with cleft palate and a noncleft control group in an obstructive sleep disordered breathing-specific tracing. SETTING: The study was conducted in the cleft palate clinic of a university hospital. PARTICIPANTS: Fifty-three subjects with a mean age of 12.3 +/- 3.7 years (range 6.3 to 17.2 years). The cohort included 33 subjects (13 females, 20 males; mean age 12.1 +/- 3.8 years, mean body mass index 17.5 +/- 2.9 kg/m(2)) with surgical closure of a unilateral or bilateral cleft palate and a matched control of noncleft participants. None of the subjects suffered from sleep disordered breathing syndrome. RESULTS: Compared with the controls, patients with cleft palate had a significant narrow anterior-posterior dimension of the pharynx at the level of the maxillary plane and the narrowest width, a more downward hyoid position, and a longer uvula. CONCLUSIONS: Patients with cleft palate appear to present pharyngeal and craniofacial distinctive features that characterize patients with obstructive sleep disordered breathing and differ from those of a noncleft control.

Dental anomalies as a microsymptom of palatal canine displacement.

AIM: A retrospective study was performed to investigate whether palatal canine displacement is associated with other dental features permitting early clinical diagnosis of the eruption disturbance. PATIENTS AND METHODS: The study was based on the complete records of 235/8556 patients at the Department of Orthodontics, School of Dental Medicine, University of Freiburg i.Br. (mean age = 14.11 years) with at least one palatally displaced permanent canine. These patients were examined for ten different morphologic parameters, e.g. impaction and congenital absence of further teeth, hypoplastic, peg-shaped, rotated and congenitally missing upper lateral incisors, supernumerary teeth, Angle classification, and cover-bite (= "Deckbiss"). The data were compared with those of a control sample of the same size with physiologic upper canine eruption (mean-age = 10.0 years). Furthermore, in a right/left comparison the local influence of anomalies of the upper lateral incisors on palatal canine displacement was evaluated by multiple linear regression analysis. RESULTS: The statistical analyses revealed that the risk of palatal canine displacement was significantly higher in patients with hypoplasia, peg shape or congenital aplasia of upper lateral incisors, further impacted and congenitally missing teeth and cover-bite. The intergroup differences in terms of gender, rotation of upper lateral incisors and Angle classification were not statistically significant. The right/left comparison revealed a significantly higher risk of palatal canine displacement in association with an adjacent hypoplastic or peg-shaped lateral incisor and with aplasia of the contralateral upper incisor. CONCLUSION: The clinical significance of the study is that the occurrence of palatally displaced canines is often closely linked with other dental anomalies. In this context, anomalies of upper lateral incisors, aplasia or impaction of further teeth, and the anomaly of cover-bite may serve as indicators of palatal canine displacement. A retarded development of the upper lateral incisor seems to be more disturbing for physiologic canine eruption than aplasia. In patients exhibiting the stated microsymptoms, close clinical follow-up of the maxillary permanent canine eruption during the late exfoliation period is strongly recommended.

3.3 Human resource management.

The most valuable of all resources in a dental teaching hospital are human intelligence and wisdom. Increasingly, universities recognize that their mission to become a centre of academic (and clinical) excellence is dependent on the most constructive and empowering use of their staff and faculty. The appropriate management and empowerment of individuals will help to maximize intellectual potential, research abilities, educational, clinical and management skills to the mutual benefit of all.

Clinical comparison of a multistranded wire and a direct-bonded polyethylene ribbon-reinforced resin composite used for lingual retention.

OBJECTIVE: The reliability of posttreatment canine-to-canine retention with resin composite retainers reinforced with plasma-treated woven polyethylene ribbons was compared to the reliability of directly bonded, multistranded wire retainers. METHOD AND MATERIALS: This prospective study was based on an assessment of 20 consecutive patients (eight women and 12 men with a mean age of 22.4 years) who required a fixed canine-to-canine retainer after undergoing orthodontic treatment. The type of retainer used was randomized for each patient. A follow-up examination was carried out once every 3 months. The length of time the retainers stayed in place without resin fracture or loosening from the teeth at one or more points was evaluated. The study's endpoint was 24 months after the retainer had been bonded. RESULTS: The ribbon-reinforced retainer remained in place for an average of 11.5 months, and the multistranded wire for a mean of 23.6 months. The difference was statistically significant. CONCLUSION: In terms of reliability for permanently fixed orthodontic retention from canine to canine, the direct-bonded multistranded wire is superior to the plasma-treated polyethylene woven ribbon and resin retainer.

Occlusal and skeletal effects of an oral appliance in the treatment of obstructive sleep apnea.

STUDY OBJECTIVE: s: Oral appliances (OAs) are considered to be a treatment option for patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). Although the effectiveness of these appliances has been evaluated in a number of clinical trials, there are few follow-up studies concerning the dental and skeletal side effects that, theoretically, could be caused by OAs. We sought to examine the long-term skeletal and occlusal effects of a nocturnally worn activator in adult patients treated for OSAHS. DESIGN: We analyzed the dental casts and lateral radiographs of 34 patients (mean age, 52.9 years; SD, 9.6 years; range, 27.1 to 64.6 years) before initiating treatment and after at least 24 months of treatment (mean length of treatment, 29.6 months; range, 24.1 to 43.5 months; SD, 5.1 months). The OA was worn by each patient 6 to 8 h nightly for > 5 days per week. SETTING: Department of Orthodontics, Dental Medical School, Freiburg, Germany. MEASUREMENTS AND RESULTS: Follow-up polysomnography studies confirmed improved breathing parameters with the use of OAs. A statistically significant alteration in the occlusion was found. The anteroposterior position of the molars and the inclination of the upper and lower incisors were changed. No skeletal changes in the position of the mandible were noted. CONCLUSIONS: The data suggest that in addition to control polysomnographic examinations, regular dental follow-up visits are mandatory when lifelong OSAHS treatment with an OA is being considered for patients with obstructive sleep apnea/hypopnea.

Cephalometric analysis in patients with obstructive sleep apnea. Part II: Prognostic value in treatment with a mandibular advancement device.

BACKGROUND: The mandibular advancement device (MAD) is accepted as an additional treatment option for snoring and mild obstructive sleep disorders. Its therapeutic efficacy can only be verified through nocturnal polysomnography with the appliance in situ. The relevance of the craniofacial skeletal and soft-tissue structures as an etiological cofactor is controversial. While the lateral cephalogram of the facial skeleton is of no direct diagnostic relevance, it remains unclear to what extent cephalometric assessment can provide prognostic information to better ensure treatment success with an MAD. METHODS AND RESULTS: This study is based on the evaluation of 57 patients diagnosed polysomnographically with obstructive sleep apnea (OSA). The patients were treated primarily with a modified activator; after 6-12 weeks, control polysomnography was carried out in the sleep laboratory. The cephalometric variables were analyzed using a multivariate regression procedure with the response variable of treatment outcome. In addition to a horizontal craniofacial morphology, the downward and forward posture of the hyoid is a prognostic variable for effective therapy with an MAD.

Corrosion susceptibility of lingual wire extensions in removable appliances. An in vitro study.

MATERIAL AND METHODS: The corrosion resistance of ten different round orthodontic wires as plastic-encased extensions was evaluated in vitro. Following the production of defined test samples with free as well as with acrylic-embedded wire segments, ten samples of each product were subjected to gap provocation by deflecting the free-running wire ends with an electric drive, while 10 samples remained provocation-free. The tests were run under standardized conditions (7 days, 37 degrees C, pH 2.3, 0.1 mol NaCl/CH3CHOHCOOH), and the findings were analyzed by stereo light microscopy and scanning electron microscopy. RESULTS: The following alterations were observed on the wire surfaces: a) crevice corrosion with substantial linear surface erosion and opaque discolorations, b) localized pitting corrosion, and c) mild surface erosion with translucent discolorations. The reactions of the test samples were similar in both those that were subjected to addition mechanical loading in the electrolyte and those that were not. Cr-Ni steels were susceptible to corrosion, whereas Co-Cr alloys as well as low-nickel manganese steels had only slight visible alterations, if any, in the embedded wire sections. CONCLUSIONS: Clinically occurring discolorations in the acrylic can be attributed to corrosion processes on the embedded wire extensions. These processes can be simulated and observed in vitro. During the processing of acrylic materials now customary in the orthodontic laboratory, crevices are inevitably formed between the wire and the acrylic, furthering the corrosion process. Our results suggest that, being more resistant to crevice corrosion, Co-Cr alloys or low-nickel steels can be considered as alternatives.

Sleep-related obstructive disordered breathing in cleft palate patients after palatoplasty.

Sleep-disordered breathing is frequently associated with children presenting congenital midface defects. Because of structural and functional anomalies in the upper airway, children with cleft palate, especially after surgery, may carry a higher risk of developing sleep-disordered breathing. However, the presence of such sleep-disordered breathing in older cleft palate children has not been emphasized. The aim of this comparative overnight cardiorespiratory sleep study was to evaluate cleft palate patients according to sleep-disordered breathing. A group of 43 cleft palate children (17 girls and 26 boys; mean age, 12.1 +/- 3.8 years) was compared with a control group of 20 randomly selected, noncleft children matched for age, sex, and body mass index. None of the patients suffered from manifest sleep-disordered breathing. Cleft palate patients had a statistically significantly higher respiratory disturbance index and snoring index, but no increased apnea index. The data suggest that cleft palate patients having undergone primary closure of the palate demonstrate microsymptoms of nocturnal upper airway obstruction.

A comparative study of two mandibular advancement appliances for the treatment of obstructive sleep apnoea.

Mandibular advancement appliances (MAAs) are accepted as a treatment option for snoring and mild obstructive sleep disorders. In the present clinical study two differently designed devices were examined for their effectiveness in treating obstructive sleep apnoea (OSA). The study was based on an assessment of 26 patients with a polysomnographic diagnosis of mild OSA [22 men, four women; mean body mass index 27.3 kg/m2 (SD 3.1); mean age 56.8 years (SD 5.2); mean respiratory disturbance index (RDI): 16.0 events/hour (SD 4.4)]. After insertion of the first MAA and a 6-8-week habituation period, a cardio-respiratory home-sleep study was carried out. Following a 2-3-week period with no treatment, the second appliance was inserted. The sequence of the devices was randomized. Once the patients had become accustomed to the second appliance, another somnographic registration was carried out. Daytime sleepiness, snoring, and sleep quality were assessed subjectively on a visual analogue scale. The results showed that a statistically significant improvement in the respiratory parameters was achieved with both appliances (P < 0.01). However, the activator [RDI: 5.5 events/hour, SD 3.3; apnoea index (AI): 3.4 events/hour, SD 2.1] was significantly more effective (P < 0.01) than the Silencor (RDI, 7.3 events/hour, SD 5.3; AI: 5.8 events/hour, SD 3.2). No difference was recorded in the subjective assessment of the therapeutic effects. Both appliances reduced daytime sleepiness and snoring and improved sleep quality, and both influenced the treatment outcome.

Treatment of obstructive sleep apnea with the Karwetzky oral appliance.

The aims of this retrospective study were to assess the effect of a Karwetzky mandibular protrusion appliance for treating patients with mild, moderate, and severe obstructive sleep apnea. Eighty-one of 116 patients (69.8%) suffering from obstructive sleep apnea were treated with an activator model according to Karwetzky. After 4 months (SD 4.0 months) treatment outcome was controlled by polysomnography. Therapeutic outcome depended on the severity of obstructive sleep apnea. The median apnea-hypopnea index decreased from 10.6 events/h (range 2.0-14.9) to 5.8 events/h (range 0.2-17.3, P<0.01) in the mild group, from 21.7 events/h (range 17.3-28.4) to 7.7 events/h (range 1.0-30.1, P<0.001) in the moderate group, and from 42.1 events/h (range 33.2-64.9) to 18.1 events/h (range 2.4-48.8, P<0.001) in the severe group. Sleep variables did not show consistent improvement except for a trend towards more REM sleep and slow-wave sleep. The numbers of retentive teeth did not statistically influence treatment efficacy. Comparing the pre- and post-treatment polysomnographic variables, it was found that the respiratory events rather than sleep stages were significantly reduced by the Karwetzky appliance investigated.