1. Field of the Invention
The present invention relates to a dental implant, and more particularly, to a method for manufacturing a surgical guide, and a crown and an abutment in a mouth for a dental implant, which precisely obtains an image of an inside of a patient's mouth, and thus enhances accuracy of the dental implant.
2. Discussion of Related Art
Generally, an implant is a substitute for a part of a human organism, when the part of the human organism is lost. However, in the field of dentistry, an implant means that an artificial tooth is implanted.
Specifically, in the case of a prosthetic appliance or a denture, other teeth and bones therearound are damaged, as time goes on. However, the implant may prevent peripheral dental tissues from being damaged, does not have secondary dental caries production factors, and thus may be safely used. Also, since the implant has a structure corresponding to a natural tooth, there are little pain in the gum region and little feeling of irritation, and it may be semipermanently used, if it is maintained well.
Meanwhile, in a dental implant, a hole is formed at an alveolar bone using a drill, and a fixture is implanted in the hole. A procedure of forming the hole and a procedure of implanting the fixture may be varied according to patients. This is because implantation position, depth and direction of the dental implant should be determined in consideration of various factors such as patient's dental conditions, a position of a tooth to be treated by the dental implant, and conditions of a patient's alveolar bone.
Meanwhile, in a drilling operation for forming the hole at the alveolar bone, it is very difficult for not only an inexperienced dentist but also a skilled dentist to accurately estimate a depth and a direction during the operation.
Further, when a drill is inserted to more than a predetermined depth, there may be a serious problem in that a nerve of the alveolar bone may be damaged. On the contrary to this, when the drilling operation is terminated before reaching the predetermined depth, an excessive force is required to fix the fixture due to a shallow depth of the formed hole. Also, there may be other problems in that a screw thread around the hole is damaged, or the fixture is not completely fixed, and thus a reoperation is required later.
Therefore, an aid tool referred to as a surgical guide is used to grasp an accurate position and direction for performing the drilling operation.
Meanwhile, FIG. 1 is a flowchart illustrating a method for manufacturing a conventional surgical guide.
As illustrated in FIG. 1, in the conventional surgical guide, a three-dimensional image of an inside of a patient's mouth is obtained through CT scanning, and a three-dimensional exterior image of the inside of the patient's mouth is obtained through oral scanning (s1).
Here, the three-dimensional image obtained through the CT scanning includes internal tissue information of shapes of a crown, a tooth root and an alveolar bone, and bone densities thereof. Also, the three-dimensional external shape image obtained through the oral scanning includes exterior information of the crown and a gum in the mouth.
When each image is obtained, the two images are matched with each other based on a point in the mouth set by an operator (s2). Then, a dental implant plan is established through an image matching result (s3), and the surgical guide which may guide a procedure according to the dental implant plan is manufactured (s4).
Here, it is preferable that the surgical guide be manufactured using external shape data of oral tissues together, rather than using only the three-dimensional image through the CT scanning.
Specifically, the three-dimensional external shape image is obtained by combining information scanned while an oral scanner is moved along the inside of the patient's mouth, and includes overall shapes of the crown of the tooth and the gum. However, in a process in which the scanned information is combined, a curvature of a tooth arrangement may be indicated in a distorted state which is different from an actual inside of the mouth, and thus an image correction process is required. Like this, to supply scarce information and to correct distorted information in each image, an image matching process in which the two images are matched with each other is necessarily required.
Here, a common portion between the two images, such as a crown region, is needed to match the three-dimensional image with the three-dimensional external shape image. However, in the case of an edentulous patient, since the crown region is lost, it is substantially difficult that the common portion between the three-dimensional image and the three-dimensional external shape image exists. Therefore, there are some problems in that it is difficult to match the images, and even though the images are matched with each other, inaccurate information is included in a matched image.
Also, when a lower jaw in the mouth is edentulous, the exposed gum region is increased, and movement tissues such as a tongue are distributed, and movability of the tissues is increased, and thus it is difficult for a scanned image to be clearly specified. Therefore, there is a problem in that it is difficult to obtain a precise external shape through the oral scanning.
Also, even when a reference marker used as a reference point of the image matching is provided at the inside of the mouth, there is another problem in that the reference marker is not substantially fixed due to the movability of the tissues. Therefore, in the image matching process, even though the images are matched with each other using the reference marker as a matching reference point, reliability of the obtained image is lowered.
Meanwhile, when a crown of the implant for replacing a lost tooth in the patient's mouth is designed, a height, a width, a masticating surface and a masticating direction of the crown are calculated based on information of teeth remaining around the lost tooth. However, in the case of the edentulous patient, since there are not the peripheral teeth as comparable objects, the crown is designed through operator's experience or existing procedure data.
However, when such manufactured crown is implanted in the patient's mouth, the patient often feels uncomfortable. Also, since a plurality of crowns should be manufactured, and the implanting process should be repeated to correct the discomfort, a procedure cost is increased. Thus, a period of time for the dental plant is extended, and it causes patient's inconvenience.