Biomechanical effects of a mandibular advancement device on the temporomandibular joint.

PURPOSE: Mandibular advancement devices are commonly used in the treatment of patients with mild to moderate obstructive sleep apnea (OSA). Designed to maintain the mandible in forced protrusion while being worn, mandibular advancement devices (MADs) are intended to increase the upper airway during sleep, thereby reducing OSA symptoms. Depending on the extent of mandibular protrusion, side effects including temporomandibular joint dysfunction are frequently reported. These are likely to reduce overall treatment success by affecting therapeutic adherence. MATERIAL AND METHODS: To investigate the biomechanical effects of an MAD on the temporomandibular joints, we used a biomechanical model of the human masticatory system. Alterations to the model were applied to mimic the effects of a titratable duoblock MAD. The extent of mandibular protrusion was simulated up to 10 mm in steps of 1 mm. Compression and shear stresses on the temporomandibular structures were predicted during an open-close maneuver and in neutral position. RESULTS: As the extent of mandibular advancement increased, the mandibular condyle migrated anteriorly until passing the articular tubercle. Stress on the temporomandibular joint structures did not considerably increase in rest whatever the extent of mandibular advancement. However, closure of the jaw required extra muscle force as mandibular advancement increased. CONCLUSION: Results from this study suggest that temporomandibular dysfunction following MAD wearing might be related to altered muscle dynamics rather than changes due to increased stress in the temporomandibular joint itself.

The role of the tensor veli palatini muscle in the development of cleft palate-associated middle ear problems.

OBJECTIVE: Otitis media with effusion is common in infants with an unrepaired cleft palate. Although its prevalence is reduced after cleft surgery, many children continue to suffer from middle ear problems during childhood. While the tensor veli palatini muscle is thought to be involved in middle ear ventilation, evidence about its exact anatomy, function, and role in cleft palate surgery is limited. This study aimed to perform a thorough review of the literature on (1) the role of the tensor veli palatini muscle in the Eustachian tube opening and middle ear ventilation, (2) anatomical anomalies in cleft palate infants related to middle ear disease, and (3) their implications for surgical techniques used in cleft palate repair. MATERIALS AND METHODS: A literature search on the MEDLINE database was performed using a combination of the keywords "tensor veli palatini muscle," "Eustachian tube," "otitis media with effusion," and "cleft palate." RESULTS: Several studies confirm the important role of the tensor veli palatini muscle in the Eustachian tube opening mechanism. Maintaining the integrity of the tensor veli palatini muscle during cleft palate surgery seems to improve long-term otological outcome. However, anatomical variations in cleft palate children may alter the effect of the tensor veli palatini muscle on the Eustachian tube's dilatation mechanism. CONCLUSION: More research is warranted to clarify the role of the tensor veli palatini muscle in cleft palate-associated Eustachian tube dysfunction and development of middle ear problems. CLINICAL RELEVANCE: Optimized surgical management of cleft palate could potentially reduce associated middle ear problems.

Management of obstructive sleep apnea in edentulous patients: an overview of the literature.

PURPOSE: A high prevalence of obstructive sleep apnea (OSA) is seen in edentulous individuals. Treatment options for edentulous OSA patients however are limited with continuous positive airway pressure therapy (CPAP) remaining the current therapy of choice. As CPAP is associated with high non-adherence rates and oral appliance therapy requiring sufficient dentition, there is a clinical need for effective treatment strategies aimed at edentulous OSA patients. The purpose of this study was to present a thorough overview of the literature regarding (1) the effects of nocturnal denture wearing on OSA, (2) the outcomes of oral appliance therapy, and (3) surgical treatment in edentulous OSA patients. METHODS: A computer-assisted literature search was performed in the MEDLINE database on "edentulism" and "obstructive sleep apnea." The search yielded a total of 34 original articles. RESULTS: A total of 20 studies were included after exclusion of non-relevant, duplicate, and non-English publications, comprising 4 randomized clinical trials, 12 case reports, and 4 cohort or cross-sectional studies. The outcomes of these studies were addressed in detail concerning nocturnal wearing of dentures, oral appliance therapy, and surgical treatment. CONCLUSION: Currently, there is no consensus in the literature on the effects of nocturnal wearing of dentures on OSA. Several studies report the successful use of oral appliance therapy, including implant-retained mandibular advancement devices (MADs), in selected cases of edentulous patients with varying stages of OSA. Little evidence is available regarding outcomes of surgical procedures in edentulous patients. Based on the results of this literature overview, the paucity of effective evidence-based treatment strategies for edentulous OSA patients indicates the further need of clinical studies to improve clinical management.

Factors Associated with Patient Delay in Scaphoid Nonunions.

Delay in seeking medical attention by patients, ─so-called patient delay, contributes to the relative high rate of delayed diagnosis and treatment in scaphoid nonunion cases. In this retrospective study we investigated the incidence of patients with a patient delay exceeding 6 months, thus by definition having an established nonunion. In addition to this, we investigated demographic, injury and patient related factors associated with this patient delay in scaphoid nonunion patients. We included 101 patients with established scaphoid nonunions treated surgically at our specialized hand surgery unit. Information regarding demographic and injury characteristics, and subjective patient related factors was obtained from medical records and a questionnaire-based survey. Sixty-four patients (63 %) responded to our survey. A quarter (25 %) of the patients showed a delay of more than 6 months. Demographic and injury characteristics were not related to this delay. In contrast to this, not attributing post-injury symptoms to a fracture but to e.g. a sprain instead, showed to be an independent predictor of patient delay. We report a high incidence of patients with an established scaphoid nonunion who delayed seeking medical attention. As there appears to be no demographic or injury characteristics associated with this patient delay, future developments of strategies to reduce patient delay should be targeted on all patients with a suspected scaphoid injury.

Juxtarenal aortic aneurysm repair.

OBJECTIVES: Juxtarenal aortic aneurysms (JAA) account for approximately 15% of abdominal aortic aneurysms. Despite advances in endovascular aneurysm repair, open repair requiring suprarenal aortic cross-clamping is still the treatment of choice for JAA. We performed a systematic review of the literature to determine perioperative mortality and postoperative renal dysfunction after open repair for non-ruptured JAA. METHODS: The Medline, Embase, and Cochrane databases were searched to identify all studies reporting non-ruptured JAA repair published between January 1966 and December 2008. Two independent observers selected studies for inclusion, assessed the methodologic quality of the included studies, and performed the data extraction. Study heterogeneity was assessed using forest plots and by calculating the between-study variance. Outcomes were perioperative mortality, postoperative renal dysfunction, and new onset of dialysis. Summary estimates with 95% confidence interval (95% CI) were calculated using a random effects model based on the binomial distribution. RESULTS: Twenty-one non-randomized cohort studies from 1986 to 2008, reporting on 1256 patients, were included. Heterogeneity between the studies was low. The mean perioperative mortality was 2.9% (95% CI, 1.8 to 4.6). The mean incidence of new onset of dialysis was 3.3% (95% CI, 2.4 to 4.5). Incidence of postoperative renal dysfunction could be derived from 13 studies and ranged from 0% to 39% (median, 18%). In seven studies, cold renal perfusion during suprarenal clamping was performed in order to preserve renal function; however, based upon the included data, definitive conclusions regarding its efficacy could not be drawn. CONCLUSIONS: Open repair of non-ruptured JAA using suprarenal cross-clamping can be performed with acceptable perioperative mortality; however, postoperative deterioration of renal function is a common complication. Preservation of renal function after JAA repair requires further investigation.

Direct videoscopic approach to the thoracic aorta for aortic endograft delivery: evaluation in a human cadaver circulation model.

PURPOSE: To examine the feasibility of a direct videoscopic approach to the descending thoracic aorta for branched endograft delivery to the aortic arch and abdominal aorta. METHODS: Aneurysms were created in the aortic arch and pararenal aorta of 3 human cadavers, and pulsatile flow was established using a roller pump. Thoracoscopically, 2 double-felted purse-string sutures were placed on the thoracic aorta. Via the most distal trocar, an endoscopic needle was used to insert a stiff guidewire into the aorta through the center of the purse-string suture. Under direct videoscopic control, a 20-F sheath was advanced over the wire into the aorta. Switching to fluoroscopic control, a fenestrated endograft was deployed in the aortic arch followed by placement of a branch graft into the left subclavian artery. The delivery sheath was withdrawn from the aorta while simultaneously tightening the purse-string sutures. A similar procedure was performed in the same cadaver for antegrade branched endograft delivery to the pararenal aorta. Correct deployment of the branched endografts was evaluated by post implant angiography and autopsy. RESULTS: The procedure was successfully completed in all cadavers. "Hemostasis" was obtained in all cadavers without aortic cross clamping. Median fluid loss was 165 mL. Autopsy proved all purse-string sutures to be adequately placed and all branched endografts to be deployed in the correct position. CONCLUSION: A direct videoscopic approach to the descending thoracic aorta proved a feasible technique for branched endograft delivery to the aortic arch and abdominal aorta in a human cadaver model.