Abstract: A bone plate system is provided that includes bone plates and bone anchor assemblies for being inserted into bone plate bores to secure the bone plates to one or more bones. In one aspect, the bone plate system includes a bone anchor assembly having a locking cap and a locking fastener connected to a head portion of a bone anchor. The bone anchor assembly is driven into a bone plate bore before the locking fastener is shifted to expand the locking cap and fix the bone anchor assembly within the bore. In another aspect, the bone plate system includes a bone anchor assembly having a locking cap that deflects radially inward due to contact with the bone plate at large bone anchor assembly insertion angles. In addition, a bone anchor assembly having a preassembled condition with a locking cap resisting back out of a locking fastener.

Abstract: Devices and methods for aligning the components of polyaxial screws are described herein. In one embodiment, an alignment instrument includes an elongate frame having a longitudinal axis and a plurality of connection caps slidably disposed along the elongate frame. Each connection cap can removably couple to a polyaxial screw extension tube and selectively lock relative to the elongate frame such that a distance between the plurality of connection caps and an angular orientation of each connection cap relative to the elongate frame is maintained. The instrument can also include a transverse angle indicator to indicate an angular orientation of the elongate frame in a plane transverse to the longitudinal axis of the elongate frame. The device can, for example, capture the orientation of a plurality of polyaxial screws during spinal surgery such that the screws can be returned to the same orientation after manipulation to correct a spinal deformity, etc.

Abstract: Methods of applying a locking cap to a bone anchor assembly. The bone anchor assembly includes a bone anchor and an elongate rod. The bone anchor includes a body that defines a channel and has a tissue retractor coupled thereto that defines a partial pathway to the channel.

Abstract: Various polymeric materials and delivery systems are described, along with systems and methods for using them for bone and tissue augmentation, such as for the stabilization and/or correction of spinal compression fractures.

Abstract: A bone repair device includes a plate having a pathway and a flexible structure. The plate includes opposing top and bottom surfaces and a first side extending between the top and the bottom surfaces. The flexible structure is directly attached to and extends from the first side of the plate. In operation, the bone repair device is placed around and over a plurality of bone parts. The plate is secured to the plurality of bone parts with a cable inserted through the pathway and wrapped around the bone parts.

Abstract: Attachment devices and methods of using the same are disclosed. The attachment devices can be fenestrated. The fenestrations can control the flow of fluid out of and/or into the device.

Abstract: A kyphoplasty cannula includes a shaft extending between opposite first and second end surfaces. The shaft includes an inner surface defining a lumen. The shaft includes a first opening that extends through the first end surface and a second opening that extends through the second end surface. A scoop extends from the second end surface. The scoop includes an arcuate surface that is continuous with the inner surface. Kits and methods of use are disclosed.

Abstract: A screw guide assembly includes a guide body extending along a central longitudinal axis. The guide body has a proximal end portion having an attachment face extending perpendicular to the longitudinal axis and a distal end portion having a screw support member extending away from the longitudinal axis. The screw support member is configured to allow for the insertion of a screw at an angle oblique relative to the longitudinal axis. A wire guide is removably inserted into the screw support member. A method of inserting a screw using the assembly is also disclosed.

Abstract: A point of incision is created within tissue, the tissue having a temporoparietal fascia-deep temporoparietal fascia layer (TPF-sDTF) beneath skin and a temporal branch of a target nerve extending along a portion of the TPF-sDTF, the point of incision being laterally displaced from the target nerve. A cryogenic probe having a distal tip extending from an elongated body is inserted into the point of incision. The TPF-sDTF is bluntly dissected using the cryogenic probe such that a treating portion of the cryogenic probe is directly adjacent to a first treatment portion of the target nerve. The cryogenic probe is activated to create a first treatment zone at the first treatment portion of the target nerve to cause a therapeutic effect.

Abstract: A system and method for providing greater control over the temperature of a thermal treatment element of a medical device, enabling an operator to extend a thawing period of a cryoablation procedure. The system may include a fluid flow path that bypasses a subcooler, giving the operator selective control over the temperature of refrigerant delivered to the treatment element and, therefore, treatment element temperature. Additionally or alternatively, the system may include a fluid delivery conduit that is in communication with a liquid refrigerant and a gaseous refrigerant. Adjustment of the ratio of liquid to gaseous refrigerant also offers control over the treatment element temperature. Additionally or alternatively, the system may include one or more valves and/or heating elements in the fluid delivery and recovery conduits to control the treatment element temperature.

Abstract: An electrosurgical dissection apparatus is disclosed, and includes a thermally insulating body, a thermally conductive insert, at least one active electrode, and at least one return electrode. The at least one active electrode is disposed on the thermally conductive insert, and the at least one return electrode is spaced from the at least one active electrode by a portion of the thermally insulating body. The thermally conductive insert is configured to cauterize tissue dissected by radiofrequency energy passing from the at least one active electrode to the at least one return electrode.

Abstract: The present disclosure provides a surgical instrument that includes an end effector having a first jaw, a second jaw that is movable relative to the first jaw, and at least one electrode in the first jaw. The surgical instrument also includes a control circuit configured to provide electrosurgical energy to the at least one electrode and a electrical conductor electrically connected between the end effector and the control circuit. The control circuit includes a shaft control segment and an electrosurgical energy control segment. The shaft control segment is configured to provide a control signal for operating the end effector to the end effector through the electrical conductor. The electrosurgical energy control segment is configured to provide the electrosurgical energy to the at least one electrode through the electrical conductor.

Abstract: Various exemplary methods, systems, and devices for controlling electrosurgical tools are provided. In exemplary embodiments of methods, systems, and devices provided herein, a control system can be configured to monitor an electrical parameter during end effector closure, e.g., as jaws of an end effector of an electrosurgical tool move from an open position to a closed position. In response to the electrical parameter dropping to a predetermined minimum parameter threshold, the control system can be configured to cause the end effector to open.

Abstract: An electrosurgical system can include an electrosurgical generator, a feedback circuit or controller, and an electrosurgical tool. The feedback circuit can provide an electrosurgery endpoint by determining the phase end point of a tissue to be treated. The electrosurgical system can include more than one electrosurgical tool for different electrosurgical operations and can include a variety of user interface features and audio/visual performance indicators. The electrosurgical system can also power conventional bipolar electrosurgical tools and direct current surgical appliances.

Abstract: A radiofrequency ablation electrode needle includes at least one first segment and at least two second segments. The at least one first segment and the at least two second segments are exposed on a surface of the needle body. An impedance of the at least one first segment is smaller than an impedance of the at least two second segments and at least one of the at least one first segment is disposed between two immediately adjacent ones of the at least two second segments. Besides, the radiofrequency ablation electrode needle is a monopolar electrode needle.

Abstract: Systems and methods for facilitating assessment of a nature of contact between an electrode assembly of an ablation catheter and viable body tissue are disclosed herein. In some embodiments, a method comprises obtaining a first detected voltage between a first electrode and a second electrode, wherein the first and second electrodes are positioned along an electrode assembly of the ablation catheter, and wherein the first electrode is distal to the second electrode, obtaining a second detected voltage between the second electrode and a third electrode, the third electrode positioned proximal to the second electrode.

Abstract: The present disclosure provides a system with an innovative electrode designed as an RF/microwave antenna as well as methods to monitor/assess biological tissue and perform surgical procedures.

Abstract: Exemplary methods and systems can be provided for resurfacing of skin that include formation of a plurality of small holes, e.g., having widths greater than about 0.2 mm and less than about 0.7 mm or 0.5 mm, using ablative electromagnetic radiation, e.g., optical energy. An optically transparent plate or window can be pressed over a surface of the skin tissue as the holes are ablated to disrupt formation of a thermal cuff around the holes. Compressive or tensile forces can then be applied to the treated region of the skin tissue as the damage heals to facilitate hole closure and provide enhanced and/or directional shrinkage of the treated skin area.

Abstract: A surgical laser system can include a fluorescent sensing assembly for detecting fluorescent signal from a tissue under a surgical operation of the surgical laser system. The surgical laser system can include an aiming laser assembly, which can be configured to provide excitation energy for the fluorescent process. The surgical laser system can include an infrared sensing assembly, which can provide temperature related data, for example, to prevent damages to the tissue due to overheating. The surgical laser system can be configured to use the off-time of the surgical laser for tissue sensing. Data from tissue sensing can be further analyzed by an integrated robotic surgical system to provide a highly precise surgical procedure.

Abstract: The present disclosure provides, according to some embodiments, methods and systems for selectively reducing, blocking or inhibiting at least part of the neural activity in an organ of a subject. In preferred embodiments, the method and system are used for selectively blocking at least part of the neural activity in a duodenum of a subject in need thereof. According to some embodiments, the selective blocking occurs through use of laser radiation. According to some embodiments, the selective blocking comprises causing damage to at least part of sensory nerves located within a target area while maintaining functional activity of tissue surrounding the sensory nerves. According to some embodiments, the sensory nerves include neurons configured to transmit signals triggered by food passing through the duodenum, such as, but not limited to, neurohormonal signals.

Abstract: Methods, systems and devices for pre-operatively planned shoulder surgery guides and implants. Pre-operative planning methods for designing glenoid placement guides and depth-control pins based on considerations of multiple factors affecting the outcome of shoulder surgery. Methods of using surgery guides and implants, including glenoid placement guides and depth-control pins, in patients undergoing shoulder surgery.

Abstract: A system and method for Brugada syndrome epicardial ablation comprising preparing an endocardial duration map; preparing a baseline epicardial duration map comprising at least one or more areas of delimination; and when some of the areas of delimination are greater than 200 ms, performing epicardial ablation of the areas of delimination greater than 200 ms. The method may further comprise preparing an updated epicardial duration map after performing epicardial ablation, and determining whether or not a BrS pattern appears in the updated epicardial duration map; and when the BrS pattern appears, performing epicardial ablation. The method may further comprise preparing an updated epicardial duration map after performing epicardial ablation, and determining whether or not an abnormal EGM exists in the updated epicardial duration map; and when the abnormal EGM exists, performing epicardial ablation.

Abstract: Systems and methods for intraocular lens selection include receiving, by one or more computing devices implementing a prediction engine, pre-operative multi-dimensional images of an eye; extracting, by the prediction engine, pre-operative measurements of the eye based on the pre-operative images; estimating, by the prediction engine using a prediction model based on a machine learning strategy, a post-operative position of an intraocular lens based on the extracted pre-operative measurements; selecting a power of the intraocular lens based on the estimated post-operative position of the intraocular lens; and selecting the intraocular lens based on the selected power. In some embodiments, the systems and methods further include receiving post-operative multi-dimensional images of the eye after implantation of the selected intraocular lens, extracting post-operative measurements of the eye, and updating the prediction model based on the pre-operative measurements and the post-operative measurements.

Abstract: A registration apparatus registers an elongated introduction element (18), like a catheter or a needle, during an interventional procedure, for instance, a brachytherapy or a biopsy. A guide element (13) includes at least one opening which guides the introduction element when being introduced into a living being (2) through the opening. A temperature profile generation element (14) associated with the opening generates a characteristic temperature profile at the opening for being transferred to the introduction element when being present in the opening. A temperature determination unit (15) determines a temperature along the introduction element, and a registration unit (16) registers the introduction element. The registering includes identifying the transferred characteristic temperature profile on the introduction element based on the determined temperature. This allows the registration unit to register the introduction element during the introduction process in a simple and efficient manner.

Abstract: An apparatus includes a processing assembly, a plurality of field generators, and a patient tracking assembly. The patient tracking assembly includes a sensor assembly and a communication assembly. The sensor assembly includes a first body, a first sensor, and an electrical conduit. The first body selectively attaches to a patient. The first sensor is mounted to the first body and generates a signal in response to movement within an electromagnetic field. The communication assembly includes a second body and a cable. The second body rotates relative to the first body from a first rotational position to a second rotational position. The cable extends away from the second body. The cable communicates with the processing assembly. The electrical conduit couples the first sensor with the cable while the casing is in the first rotational position and the second rotational position.

Abstract: A foot pedal assembly for controlling a robotic surgical system. The foot pedal assembly including a foot pedal base, a foot pedal and a sensor. The foot pedal moves relative to the foot pedal base and has a contact surface extending from a distal end to a proximal end of the foot pedal. The contact surface is to come into contact with a foot of a user during use of the foot pedal assembly for controlling the robotic surgical system and the distal end is farther away from a heel of the foot than the proximal end during use of the assembly for controlling the robotic surgical system. The sensor is coupled to the contact surface of the foot pedal at a position closer to the proximal end than the distal end, and the sensor is operable to sense a target object positioned a distance over the contact surface.

Abstract: A surgical robot for performing minimally invasive surgery (e.g. in the eye) is provided. A cannula connection is positioned at a fixed surgical arm part and aligned with a movable surgical arm part movable with respect to the fixed surgical arm part. A surgical instrument can be mounted at the movable part. The surgical instrument can pass through the cannula connection. Reference arm(s) and manipulation arm(s) connect a base element with the fixed surgical arm part. The base element could have a surgical operating table attachment part to movably attach to a surgical operating table and rotating parts movably attached to the surgical operating table attachment part.

Abstract: A calibration device for a computer-assisted surgical instrument includes a rigid body, stabilization members, and references structurally or mechanically complementary to the stabilization members and disposed on opposite sides of a manipulator of the instrument. Kinematic state of the manipulator is defaulted when the calibration device is connected to the instrument by the stabilization members passing through the rigid body and removably attaching to the references. A calibration method for a computer-assisted surgical instrument implemented by a computer system includes the steps of: prompting a user to connect the calibration device to the instrument; determining if the calibration device is properly connected to the instrument; and generating default kinematic information of the manipulator of the instrument if the calibration device is properly connected to the instrument. The calibration device and method effectively improve accuracy and precision of computer-assisted surgeries.

Abstract: A robotic surgical system can include one or more adjustable arm supports that support one or more robotic arms. The adjustable arm supports and/or robotic arms can be configured to be deployed from low mount positions, for example, from positions below the surface of the table. The robotic arms can include a plurality of joints providing a plurality of degrees of freedom. The joints may be grouped into a proximal shoulder, an elbow, and a distal wrist. The robotic arms can include one or more redundant degrees of freedom. An insertion mechanism, associated with the robotic arm and configured for providing insertion of an instrument along an assertion axis, can be provided at a distal end of the robotic arms.

Abstract: An articulation assembly for a surgical instrument, surgical instrument including the same, and robotic surgical system including a surgical robot and the surgical instrument including the articulation assembly. The articulation assembly includes lead screw assemblies each including a lead screw and a collar operably engaged about the lead screw such that rotation of the lead screw translates the collar about the lead screw. Articulation cables are operably coupled to the collars of the lead screw assemblies such that proximal movement of one of the collars about the respective lead screw tensions the corresponding articulation cable and such that distal movement of one of the collars about the respective lead screw de-tensions the corresponding articulation cable. Proximal gear assemblies are coupled to the lead screws. Coupling gears couple pairs of the proximal gear assemblies with one another to maintain a pre-tension on the corresponding articulation cables.

Abstract: A medical-manipulator rotation mechanism includes: a cylindrical rotator that is fixed to a treatment part at the distal end and that is supported so as to be rotatable about the longitudinal axis; a long power-transmitting member wound around the rotator; and a folding part that bends the power-transmitting member led out in a tangential direction from the rotator and guides the power-transmitting member toward the proximal-end side, wherein the power-transmitting member is led out in tangential directions at different positions between which a wound part of the rotator around which the power-transmitting member is wound exists.

Abstract: Systems and methods for arbitrary viewpoint robotic manipulation and robotic surgical assistance are disclosed. According to an aspect, a system includes one or more controllers configured to receive an image dataset of an actual environment within which the robotic tool is positioned. The controller(s) are also configured to generate a virtual environment of the actual environment based on the image dataset. Further, the controller(s) can control display of the virtual environment including a virtual tool controllable by a user for use to control the robotic tool within the actual environment. The controller(s) can receive user input for altering a perspective view of display of the virtual environment from a first perspective view to a second perspective view. Further, the controller(s) can maintain orientation of display of the virtual tool with respect to the user during display of the first perspective view and the second perspective view of the virtual environment.

Abstract: Provided is a sterile drape configured to cover a medical observation apparatus to keep the medical observation apparatus sterile, the medical observation apparatus including a microscope part configured to magnify and image a microfine site of an observation object, an input part configured to receive an input of an operation instruction to the microscope part, and a grip part having a bar shape and having a surface provided with at least a portion of the input part, the sterile drape including: an attaching part configured to be fixed and attached to the grip part in a state where the sterile drape covers the medical observation apparatus.

Abstract: The present invention concerns an elongated medical device (1) suitable for intravascular insertion. Said device comprising a flexible elongated body (2) having a distal portion (3) with a distal end (4) and a proximal portion (5) and an optic force sensing assembly (20) disposed within said flexible elongated body (2) proximate said distal end.

Abstract: A stand apparatus, which can be built and assembled/disassembled in a modular manner, is shown and described. In particular embodiments, a bushing for a stand apparatus for arrangement in an operation theater, comprising a coupling part, by means of which the bushing can be mounted on a connecting component of the stand apparatus about a rotational axis and/or along the rotational axis in a height-adjustable manner—in particular, on a spindle—and a section on which the bushing can be connected to a support arm of the stand apparatus, wherein the section is a mounting section, by means of which the bushing can be mounted on the support arm in a reversible manner—in particular, by means of one or more fastening means. Further embodiments comprise a support arm for fastening to a bushing, as well as a support system, consisting of at least one such bushing and one such support arm.

Abstract: A cleaning swab device and method for cleaning a fluid coupling or connector. The device includes a generally elongate cylindrical tubular swab body, and a channel formed at an end thereof to define at least one cleaning finger for insertion into a housing and/or port of the connector to remove residual fluids, clean and disinfect the connector. The cleaning device optionally further includes a guide stem or plunger configured to extend through the tubular body of the swab, having a plug at one end for sealing debris out of a lumen of the connector during cleaning.

Abstract: Apparatuses and methods to physically couple a transponder to a surgical object are provided. One example apparatus includes a first clamp comprising a first fastener and a first channel member that has a first base and a first pair of side portions that extend from the first base to form a first channel therebetween. The first fastener adjustably engages with the first channel member to securingly clamp a surgical object in the first channel of the first channel member. The apparatus further includes a housing that has at least a first cavity that receives at least a portion of the first pair of side portions of the first channel member, a first passageway that receives the first fastener and permits the first fastener to extend at least in part into the first cavity, and a second passageway to receive at least one transponder that wirelessly receives and returns signals.

Abstract: Embodiments relate to adding customized cut line information to a shell that is to be formed over mold of a dental arch. In one embodiment, a cut line is determined for the shell. A processing device determines one or more markings for the shell that will mark the cut line. The processing device determines one or more features to add to the mold over which the shell will be formed that will cause the shell to have the one or more markings. The processing device generates a digital model of the mold, the digital model comprising the one or more features, wherein the digital model is usable to manufacture the mold having the one or more features.

Abstract: Detection of placement of dental aligners in patient mouth on teeth for indication of wearing compliance. Described herein are apparatuses and methods for detecting wearing, including compliance. In some variations these apparatuses and methods may include a sensor configured to detect deflection of the one or more deflectable structures. In some variations, these apparatuses and methods may include a proximity sensor coupled to the appliance shell and configured to generate sensor data when in proximity with intraoral tissue.

Abstract: Methods, systems, and apparatuses are described for determining a boundary between teeth and gingiva of an archform and/or between teeth and other teeth. Curves may be defined on the surface of teeth and gingiva in the archform. A predicted likelihood parameter that each of the points corresponds to the boundary between the teeth and gingiva may be determined. A smoothing function and the predicted likelihood parameter may be used to determine a boundary point for each curve. The boundary points may be connected to form the boundary between the teeth and gingiva.

Abstract: A ceramic implant which has a ceramic, endosseous surface region that is intended to be embedded into the bone tissue and that is made of a ceramic material. The surface region has at least one first zone having a surface modification, in which first zone the surface is roughened or porous, and at least one second zone, in which the surface is not roughened or porous.

Abstract: A system comprises a scanner, an augmented reality (AR) display and a computing device. The scanner generates intraoral images of a dental arch and the AR display generates additional image data representative of a view from a wearer of the AR display. The computing device receives the intraoral images from the intraoral scanner, generates a virtual three-dimensional model of at least a portion of the dental arch from the intraoral images, receives the additional image data from the AR display, determines, from the additional image data, a region of the view that is outside of the dental arch, generates a visual overlay comprising the virtual three-dimensional model, and sends the visual overlay to the AR display. The AR display displays the visual overlay such that the virtual three-dimensional model is shown in the region of the view that is outside of the dental arch.

Abstract: Methods and apparatuses for generating a model of a subject's teeth. Described herein are intraoral scanning methods and apparatuses for generating a three-dimensional model of a subject's intraoral region (e.g., teeth) including both surface features and internal features. These methods and apparatuses may be used for identifying and evaluating lesions, caries and cracks in the teeth. Any of these methods and apparatuses may use minimum scattering coefficients and/or segmentation to form a volumetric model of the teeth.

Abstract: Methods and systems for scanning an intraoral cavity of a patient provide capturing one or more viewfinder images of the intraoral cavity and scanning the intraoral cavity with an intraoral scanner to generate one or more topography scans of the intraoral cavity. The one or more topography scans may correspond to the one or more viewfinder images. The methods and systems further provide capturing a viewfinder image of a portion of the intraoral cavity, the viewfinder image overlapping with the one or more viewfinder images. An area of overlap of the viewfinder image with the one or more viewfinder images can be determined. One or more indicators of the area of overlap can be displayed on one or more locations of a display in order to provide guidance for positioning a field of view of the intraoral scanner.

Abstract: A mobile linked implant diagnosis system includes an implant diagnosis apparatus acquiring synthetic three-dimensional (3D) image data about a mouth area of a target patient and generating implant surgery planning data, in which virtual implant data is overlapped on the synthetic 3D image data, based on the synthetic 3D image data, a server apparatus connected to the implant diagnosis apparatus in a wired or wireless manner, and receiving information of interest that is part of the implant surgery planning data generated in the implant diagnosis apparatus and storing the information of interest, and a mobile device connected to the server apparatus in a wired or wireless manner, and receiving the information of interest from the server apparatus and displaying the information of interest. The information of interest comprises partial 3D image data of the implant surgery data, the partial 3D image data being data about a preset area around the virtual implant.

Abstract: An interdental brush (1) comprises a body (4) with a handle (5) and a guide channel (7). Also provided is a connecting element (9), which connects a cleaning body (3) to an operating element (6). The connecting element (9) with the cleaning body (3) can be displaced in a reciprocating manner within the guide channel (7), by means of the operating element (6), between a retracted position, in which the cleaning body (3) is arranged within the guide channel (7), and an extended position, in which the cleaning body (3) projects out of the guide channel (7) at a distal end of the guide channel (7), as seen in relation to the handle (5). A flexible positioning element (2) is provided at the distal end of the guide channel (7). The positioning element (2) can be placed in an approximal space between two teeth such that the cleaning body (3), during displacement into the extended position, penetrates into the approximal space.

Abstract: The invention presented is a wedge-shaped flossing device the body of which includes a tapered top edge extending between the first end and the second end and a bottom edge extending perpendicularly from said first end to said second end. A cleaning point is formed by the second end and a lead point extends below the bottom edge. The bottom edge of the device may incorporate a guide groove. The device can be disposable and may be coated with appropriate dental coatings.

Abstract: A sonic vibration toothbrush includes a head extending in an axial direction with a plurality of bristles implanted at an outer circumference thereof in a direction perpendicular to the axial direction; a head arm having an inner space to transmit a sonic wave to the head. A top portion of the head arm where the inner space is narrowed is coupled to the head and a motor accommodating portion that accommodates a motor therein and transmits a sonic wave generated by a rotating force of the motor to the head arm. The toothbrush further includes a handle having a space for accommodating a battery; an input unit provided at the motor accommodating portion in a button form; a display unit provided at the handle; and a control circuit that controls the motor according to input information provided from the input unit.

Abstract: A diagnosis device provided with a position data generation unit (224) and a linking unit (226). The position data generation unit (224) generates first position data and second position data using a relative position image showing the relative positions of an upper bow and a bite-fork, an upper-part image showing the positional relationship of the bite-fork and the maxillary dental arch of a patient, and an articulation image showing the positional relationship of the maxillary dental arch and the mandibular dental arch of the patient. The linking unit (226) generates a virtual articulator by positioning three-dimensional models of the patient's maxillary dental arch and mandibular dental arch generated by a model generation unit (223), using the first position data and the second position data.

Abstract: A composite implant device for use in a medical application, comprising a synthetically-derived mesh that mimics particular critical aspects of a biologically-derived mesh. The composite implant device can be used for the reinforcement and reconstruction of tissues within the body and can be comprised of a majority of synthetic components and minority of naturally-derived components which mimic the structure and function of a naturally-derived mesh.