Clinical studies

Cam synthesis applied to the design of a customized mandibular advancement device for the treatment of obstructive sleep apnea

A. Bataller, J.A. Cabrera, M. García, J.J. Castillo, P. Mayoral

Mandibular Advancement Devices (MAD) have proved to be effective in the treatment of slight to moderate Obstructive Sleep Apnea (OSA). These devices open the upper air- ways by keeping the jaw forward with respect to its resting position. To date, none of the available devices have taken into account the kinematic behavior of each patient’s mandible. This work presents a customized MAD for the treatment of OSA. A study of the mandible kinematics is carried out to determine the relationship between mouth opening and mandible advancement. The device includes two cams, one on each side, to make the mandible move forward. The cam profile is designed using a Bezier cubic curve that is op- timized by means of an evolutionary algorithm. The kinematics of each patient’s mandible is taken into account to ensure that the jaw does not move backwards at any time while opening the mouth. A real case study is presented to validate the proposed methodology.

Antero-posterior mandibular position at different vertical levels for mandibular advancing device design.

P. Mayoral, M. O. Lagravère, M. Míguez-Contreras and M. Garcia

Mandibular Advancement Devices (MAD) have been reported to be an alternative treatment to CPAP in moderate to severe obstructive sleep apnea (OSA) cases. The design of MAD has a major influence on its success rate on the patient, and design features that have an influence on efficacy, tolerance, and compliance. The aim of this study was to determine the range of mandibular protrusion at different vertical points; 2, 5, 8 and 11mm in a young adult population.

Determining the impact of vertical dimension on the mandibular range of motion in young adults: A consideration for the design and the construction of a mandibular advancement device.

P. Mayoral Sanz, M. García Reyes, A. Bataller Torras, J.A. Cabrera Castillo, A. Fernandez Guerrero

The aim of this study was to determine the impact of the increase of vertical dimension on the range of mandibular movements in young adults. According to literature, different anterior vertical openings have been used for the design of MADs and there is still no evidence on the impact of vertical movements on the capability of the patient to advance the mandible.

Determining the mandibular normal range of motion in young adults: A guide for diagnosis and treatments of patients with mandibular advance devices.

M. García Reyes, P. Mayoral Sanz, J. Vila, M. Míguez Contreras, J. De La Cruz, N. Abiker, A. Bataller Torras, J.A. Cabrera Castillo, A. Fernandez Guerrero

The degree of mandibular protrusion is one of the key therapeutical choices of the treatment of patients affected by OSAS with Mandibular advancing devices (MAD). The aim of this study was to determine the range of mandibular maximum protrusion at 4 different anterior vertical opening (interincisal distances: 2, 5, 8, 11 mm).

Mandibular movement analisys by means of a kinematic model applied to the design of oral appliances for the treatment of obstructive sleep apnea

Marcos García, Juan A. Cabrera, Alex Bataller, Javier Vila, Pedro Mayoral

Mandibular advancement devices (MADs) are one of the treatment options used for the obstructive sleep apnea syndrome (OSAS). At present, MADs are designed with standard titration systems, without considering each patient’s anatomical characteristics of the temporomandibular joint and mandible shape. The main objective of this study is to evaluate if a variability in mandibular morphology will influence the displacement of the jaw with a MAD. Such knowledge will be of help to find optimal mandibular positions with MAD even when opening the mouth.

Normal range of maximum mandibular protrusion: first step in the design and construction of a customized mandibular advance device.

Mayoral Sanz P, Martín JV, Romero MM, Reyes MG

One important aspect of the construction of a mandibular advance device (MAD) is the advancement of the mandible. Frequently, with higher level of advancement, better treatment effect can be obtained, although potential increase of side effects should be considered and balanced. The degree of advancement is usually expressed in % of maximum protrusive capacity or/and in millimeters (mm). Percentage of maximum protrusive capacity is used in reference to potential side effects and percentage or millimeters to effectiveness in opening the upper airway. Among the studies that address the mandibular movements, just few of them have determined the normal range of this movement. Therefore, the aim of this study was to estimate the range of mandibular advance in a representative sample of adult population.

3D Kinematic Mandible Model to Design Mandibular Advancement Devices for the Treatment of Obstructive Sleep Apnea.

M. García, J. A. Cabrera, A. Bataller, S. Postigo, J. J. Castillo

Mandibular advancement devices (MADs) are one of the treatments used for Obstructive sleep apnea (OSA). MADs try to maintain the mandible in an advanced position to keep the upper airways open when sleeping. To achieve this goal, most current MADs limit the mouth opening to a few millimeters. The study of the kinematic behavior of the patient’s jaw is essential in order to design devices that allow greater aperture ranges. For this purpose, a 3D multibody model that reproduces jaw movement has been developed in this work. To this end, the movement of the lower incisor has been determined by means of a vision system and reflective markers. In addition, the kinematics of the temporomandibular joint has been modelled.
Next, the device is designed and printed using a cam-follower mechanism. This way, the cam profiles and the followers are optimally designed and positioned for each patient depending on the physiognomy of the jaw and the opening and advancing movement prescribed by the specialist.

A study of tensile and bending properties of 3D-printed biocompatible materials used in dental appliances.

Marcos Garcia Reyes, Alex Bataller Torras, Juan A. Cabrera Carrillo, Juan M. Velasco Garcia, and Juan J. Castillo Aguilar

In the last years, a large number of new biocompatible materials for 3D printers have emerged. Due to their recent appearance and rapid growth, there is little information about their mechanical properties. The design and manufacturing of oral appliances made with 3D printing technologies require knowledge of the mechanical properties of the biocompatible material used to achieve optimal performance for each application. This paper focuses on analysing the mechanical behaviour of a wide range of biocompatible materials using different additive manufacturing technologies. To this end, tensile and bending tests on different types of recent biocompatible materials used with 3D printers were conducted to evaluate the influence of the material, 3D printing technology, and printing orientation on the fragile/ductile behaviour of the manufactured devices. A test bench was used to perform tensile tests according to ASTM D638 and bending tests according to ISO 178. The specimens were manufactured with nine different materials and five manufacturing technologies. Furthermore, specimens were created with different printing technologies, biocompatible materials, and printing orientations. The maximum allowable stress, rupture stress, flexural modulus, and deformation in each of the tested specimens were recorded. Results suggest that specimens manufactured with Stereolithography (SLA) and milling (polymethyl methacrylate PMMA) achieved high maximum allowable and rupture stress values. It was also observed that Polyjet printing and Selective Laser Sintering technologies led to load–displacement curves with low maximum stress and high deformation values. Specimens manufactured with Digital Light Processing technology showed intermediate and homogeneous performance. Finally, it was observed that the printing direction significantly influences the mechanical properties of the manufactured specimens in some cases.

Kinematics of mandibular advancement devices (MADs). Why do some MADs move the jaw backwards when opening the mouth?

Juan A. Cabrera, Alex Bataller, Sergio Postigo, Marcos Garcia

Mandibular advancement devices (MADs) are one of the most widely used treatments for obstructive sleep apnea. MADs are based on advancing the jaw to open the upper airways. To increase patient comfort, most of them allow the mouth to be opened. However, not all systems keep the jaw in a forward position when opening the mouth, producing a retrusion that favors the collapse of the upper airways. Furthermore, the kinematic behavior of the mechanism formed by the mandible-device assembly also depends on the morphology of the jaw. This means that, when opening the mouth, there are devices that protrude the jaw in some patients, while they retract it in others. In this work, the behavior of the best-known devices on the market is studied. To do so, a kinematic model of the jaw-device assembly has been developed. This model has been validated for all the devices analyzed with a high-resolution camera system. The results obtained show that some of the devices analyzed do not have correct behavior when patients open their mouth.

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