Patent Application
20210196431
Embodiments of the present method and device described herein in general relates to an orthopedic device, particularly useful for advancing midface and maxillofacial bony structures. More particularly, the present method and device relates to a dentofacial orthopedic device anchored to a skull and midface. The device is capable of exerting expansive extra-oral force antero-posteriorly across cranial structures and sutures in order to advance mid-face and maxillofacial structures.
Underdevelopment of the mid-face and maxilla, which is often paired with a retruded lower jaw, affects both adults and children. It can be caused by improper development of facial and oral muscles, nose breathing patters, weak tongue musculature and tongue posture. In the case of adults, this type of underdevelopment can result in postural and temporomandibular problems, not to mention the psychological side-effects of a craniofacial deformity, and worse, obstructive sleep apnea (OSA), in which the patient's airway is too small to withstand normal soft tissue collapse during sleep, and as a result, the airway cuts off at night causing a drop of oxygen levels. A significant number of children world-wide endure cranio-facial birth defects. Mid-face deficiencies are often treated surgically, whereby an antero-posteriorly deficient maxilla, or other part of the cranium, is osteotomized and advanced.
In the treatment of OSA and underdeveloped jaws, patients often undergo double jaw surgery, in which both the upper and lower jaw are resected and moved forward, then fastened into place with screws and plates. Known in the art are the risks of relapse and injury to neurovascular structures.
Another drawback of current surgical approaches is that for people with OSA, surgical resection followed by advancement of the maxilla does not allow for multiple discrete advancements of the maxilla to optimize patency. In some surgical cases, the maximum surgical advancement in one attempt may not be enough to cure the OSA, due to limits on stretching soft tissues at once.
While double jaw surgery can advance the upper and lower jaw, it does not fully solve problems related to underdevelopment of the cranium. More specifically, there are patients with underdevelopment of the entire mid-face. Such patients may not only exhibit posteriorly positioned maxillae, but also underdeveloped eye sockets, incorrectly positioned sphenoid bones, compressed sinus cavities, retruded cranial foramina with reduced opening size, possible unusual pressure on nerves from compressed bones.
The current surgical solution of cutting and segmenting individual bony segments to advance them forward does not address the above mentioned and other effects of generalized mid-face and cranial underdevelopment.
Prior art with patent application numbers 20170312053, 20060029899 and 20050244769 describe maxillary and mid-face advancement appliances. These appliances rely on heavy elastics to deliver the pulling force against the maxilla, such elastics which may not be able to apply enough force in discrete intervals to separate cranial sutures. As well, these appliances rely on applying counter-pressure on other structures on the anterior side of the skull to pull against the maxilla, such as the forehead and the chin, and these structures may be adversely affected from such pressure. Therefore, there exists a need for a maxillary and mid-face advancement appliance that does not rely on elastics, nor on putting counter pressure on anterior structures of the skull and face.
To address the limitations of existing techniques, there is a need for a mid-facial advancement method that allows for multiple discrete advancement steps that put minimal stretching loads on soft tissues at once to reduce the risk of relapse and increase the advancement distance potential of the maxilla, that applies a ubiquitous antero-posterior force across the entire cranium in order to decompress internal structures that were previously compressed, that does not require surgical detachment and reattachment of bony structures, hence reducing the risk of neurovascular injuries, that does not rely on elastics to deliver force, and that does not require the use of counter-force against other structures that are at the anterior region of the skull, such as the forehead and chin.
The proposed device and method addresses the above problems by applying a controlled and general expansive force between the back of the head and the maxilla without the use of bony cuts and segmentations, such force that will extend through other cranial bone and neurovascular structures that may also be underdeveloped. This approach may address the above-mentioned issues of underdeveloped eye sockets, incorrectly positioned sphenoid bones, compressed sinus cavities, retruded cranial foramina with reduced opening size along with reduced cranial blood flow and unusual pressure on nerves, including others.
The proposed device applies discrete and gradual displacement force at regular intervals across cranial sutures, expanding them and stretching the soft tissues over a gradual period, potentially increasing the physiologically tolerable advancement distance. For OSA patients, this allows for periodic testing of the airway patency, as the mid-face is being advanced, giving the practitioner the knowledge of when to stop advancement.
Various embodiments of the present subject matter are applicable for various applications. One embodiment of the present subject matter is configured to be used as a dentofacial orthopedic device.
Embodiments of the present device and method described herein in general relates to a dentofacial orthopedic device, particularly useful for advancing midfacial bony structures. More particularly, the present device and method relates to a bone anchored dentofacial orthopedic device with one end anchored to the skull and other end anchored to the mid-face, either by a tooth-borne or bone-anchored appliance. The dentofacial orthopedic device, referred as to the device hereinafter, is capable of exerting expansive extra-oral force antero-posteriorly across the anchored points on the skulls and the mid-face. The device is useful in particular, but not limited to, advancing mid-face and cranial maxillofacial structures.
According to one feature of the present embodiment, a metal brace is screwed to the occipital region of the skull through at least one anchorage screw, with or without subcutaneous plates. The location of the anchorage is optimized for skull thickness and force alignment.
The metal brace is contoured to the shape of the skull, which wraps around the front of the skull, forming a ring-shaped loop around the mouth that terminates full circle in front of the mouth. At the mouth-end of the metal brace, there is a slot for an adjustable center screw that can be retracted or advanced by turning a nut. The adjustable center screw is attached to an orthodontic bracket. The orthodontic bracket is a rigid mouth piece which is either tooth-borne or bone-anchored intra orally into the maxilla, the zygoma, or onto another bony structure connected to it, or another bony structure that needs to be moved. Therefore, by turning the nut at the mouth end of the brace, the adjustable center screw can be advanced and will pull forward against the bony structures that need to be advanced or relocated. Turning the nut creates displacement forces that will be translated to the back of the skull where the brace is attached by the aforementioned screws and plates.
The slot of the metal brace, located at the front of the mouth, is fitted to the metal brace via a hinge. The slot is provided to host the adjustable center screw that can be angulated to suite the desired direction of motion of maxillary or bony structure advancement. The adjustable center screw is fitted in the slot in at a predetermined position. The position can be determined based on the midfacial bone structure, geometry of the midfacial bone, and amount of displacement force required. During a course of midfacial advancement, the screw position can be changed according to the achieved target of advancement and the expected course of the advancement.
The orthodontic bracket is configured to be angulated such that at any angle of advancement, the center of rotation is at the opening of the patient's mouth. This configuration ensures that the mouth can be sealed at any given angle of advancement. The center of rotation is the place where the adjustable center screw is fitted. By rotating the adjustable center screw, the orthodontic bracket can be angulated. Based on the desired direction of the displacement force application, the adjustable center screw can be rotated in clock wise or anti clockwise direction.
The materials of the metal brace can be titanium or any biocompatible rigid material. The orthodontic bracket too is made of similar materials such as titanium or any biocompatible rigid material.
The device may be designed by a person or an artificially intelligent software program. The device requires a planning stage, which would normally be undertaken by an oral surgeon, such stage which involves cephalometric and CT-Scan analysis, which takes into account the current position of the bones of the skull, and the desired position of those bones as determined by the patient and the practitioner. The path of movement and displacement of the mid-face is determined, and accordingly the device is designed to follow that path. Over the course of the treatment period, the angular or linear displacement of the device is achieved that results in movement of the bony structure per the results of the planning stage. Optimizing the placement of anchorage screws at the back of the skull and intraorally can be done using computer assisted surgery.
The expansive extra-oral force from the temporal bone regions separates cranial sutures, eventually pushing the midface forward.
A better understanding of embodiments of the present disclosure (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the embodiments along with the following drawings, in which:
Embodiments and features of the present invention are described herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms.
According to one embodiment, the at least one anchorage screw, with at least one subcutaneous plate (202), is screwed to the back of the skull to anchor the metal brace (102) to the skull. In another embodiment, the at least one anchorage screw (104) is screwed to the skull without a subcutaneous plate (202). The at least one anchorage screw (104) is screwed at a location that has been optimized for bone geometry, skull thickness and force alignment such that the plane of the screw-thread is as close to possible as perpendicular to the desired direction of force application.
In accordance with one feature of the preferred embodiment, an adjustable center screw (108) is rotatably coupled to the metal brace (102) at the mouth-end of the metal brace (102). The metal brace (102) is provided with a slot (116) at the mouth-end, and the adjustable center screw (108) is rotatably fitted into the slot (116). The slot may be a plurality of configurations (not shown in the figure). In one configuration, the slow can be a metal strip with multiplicity of holes. The holes can be grooved at particular distance from each other. The adjustable center screw can be adjustably fitted at a location through one of the multiplicity of holes, where the location can be determined based on required angulation of the orthodontic bracket. In another configuration, the slot can be just one vertically elongated groove. The adjustable center screw can be fitted at any given point along the vertically elongated groove with at least one bolt.
The adjustable center screw (108) can be retracted or advanced to make angular and linear displacement of an orthodontic bracket (106) by turning a nut in clockwise or anti-clockwise direction at specific angle. The specific angular position at which the adjustable center screw (108) has to be set is determined by a desired angular and linear position of the orthodontic bracket (106).
According to another feature of the preferred embodiment, the orthodontic bracket (106) is a rigid mouth piece placed inside the user's mouth. In one example of placement of the orthodontic bracket (106), the orthodontic bracket (106) can be mounted on the user's alveolar process of maxilla. In another example, the orthodontic bracket (106) can be anchored intra-orally into the maxilla, another bony structure connected to it, or another bony structure that needs to be moved. According to the preferred embodiment, the orthodontic bracket (106) is coupled to the metal brace (102) through the adjustable center screw (108).
A maxilla shaft (110) interconnects the maxilla screws at anchored ends forming a C shape loop. A maxilla joint (112) securely attaches the maxilla shaft (110) to a tail end (114) of the bracket. The maxilla joint (112) is a rotational joint allowing easy jaw movements by way of its coupling between the maxilla screws (302) and maxilla shaft (110). The tail end (114) is adjustably coupled to the metal brace (102) through the adjustable center screw (108).
Patient's bone structure, degree of midfacial deformity, bone thickness, bone geometry are the factors to be considered while predetermining the angular of linear displacement force to be applied. The predetermined displacement force is applied on the orthodontic bracket (106), in turn, the orthodontic bracket (106) retracts or advances maxilla bone as a result of linear and/or angular displacement. As one end of the metal brace (102) is anchored to occipital bone of the skull, the displacement force is transmitted to the skull as well. The displacement force cause expansion of cranial sutures. Gradual application of displacement force and expansion of cranial sutures results in separation of cranial sutures.
According to the preferred embodiment, due to rotation of the adjustable center screw (108), the orthodontic bracket (106) is displaced which results in generation of displacement force. The displacement force is transmitted to the anchorage screws through the metal brace (102). Gradual application of displacement force, at regular interval, results into expansion of cranial sutures, and eventually, into separation of cranial sutures. Separation of cranial sutures ultimately pushes maxilla forward with respect to temporal bones. Separation of cranial sutures may also result in widen opening of foramina. Wider opening of foramina may allow adequate blood flow to the brain.
It is to be noted that the rotation of the adjustable center screw (108) is highly subjective to degree of deformity of an individual. According to one aspect of the embodiment, a surgeon may keep the patient under regular observation to track the maxillary advancement. Close medical examination, for example Computed Tomography (CT) Scanning, can give clear insight of the current progress. Based on the scanning results, the surgeon can determine the required course of action. The surgeon may use computer assisted pre-operative planning tools to construe a required operative action plan. Calculated shear forces are applied on the set of cranial anchorage screws. The forces to be applied are calculated to be greater than internal retentive forces within the cranial sutures to be separated. For the calculations of determining the required shear forces, the computer operated pre-operative planning tool may consider maxillary advancement achieved, desired advancement, internal retentive forces and within the cranial sutures and maximum shear forces that the anchorage screws can withstand. The action plan is construed for gradual separation of the cranial sutures and advancement of the maxillary structure, and other structures.
The described embodiment is particularly advantageous as it does not require pre-operative surgical process of bone segmentation as required in distraction osteogenesis. The device (100) and its implementation require less surgical intervention. Strategic placements of the screws, gradual displacement force, and minimal surgical process may eradicate risk of neurovascular loss. It may also pose reduced risk of relapse. Further, as the displacement forces are applied extra-orally and antero-posteriorly to cranial foramina, gradual expansion of the opening of foramina can be observed. Expanded opening of foramina may result into increased blood flow to the brain. The described embodiment exhibits gradual incremental forward movement of the midface and maxillary structure over time, it allows the patency of the patient's airway to be tested and determined as forward midface and maxillary movement progress.
The device disclosed herein may be embodied in other specific forms without departing from their essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.
To the extent not already described, the different features and structures of the various embodiments can be used in combination, or in substitution with each other as desired. That one feature is not illustrated in all of the embodiments is not meant to be construed that it cannot be so illustrated, but is done for brevity of description. Thus, the various features of the different embodiments can be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described. All combinations or permutations of features described herein are covered by this disclosure.
| Number | Date | Country | |
|---|---|---|---|
| 62909793 | Oct 2019 | US |
