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we will continue to learn new principles and techniques for using oral mirrors on the basis of the oral mirror skills learned in the previous chapter.
Basic skills of maxillary dental arch mouth mirror
Practice time: 80 minutes
Materials to be prepared:
01. Dental surgery microscope
02. Teeth model (28 teeth)
03. Medium-sized phones
04. Crown preparation emery bur
05. Ergonomic doctor chair
06. Microscope
Goals to be achieved by the exercise:
01. Further practice oral mirror skills in the posterior area under the field of view of 2x-12x magnification
02. Understand the theory of “left and right” tooth surface
03. Preliminary study of microscope mirror clock theory
04. Learn the position of the mouth mirror from 9 o’clock to 3 o’clock
Working position of the upper left posterior area
Dental chair: Slightly raise the dental chair and adjust it so that the patient’s lower jaw plane is parallel to the ground plane, and the upper jaw plane is at a 45° angle to the ground plane.
Doctor: 11-12 o’clock.
Nurse: At 3 o’clock, put the strong pipette tip into the patient’s mouth.
Microscope: Reduce the angle between the microscope and the axial plane of the root canal.
Patient: Lying on his back, turning his head slightly to the right when treating premolars, and turning his head completely to the right when treating molars.
The above picture shows the recommended positions of doctors, nurses and patients during micro-root canal treatment in the upper left posterior area (pictures are demonstrations of positions, and rubber dams are recommended in actual treatment)
Oral mirror clock theory
The easiest way to understand the clock of the mouth mirror is to place the mouth mirror on the 14 teeth. The center of the surface represents the field of view of the microscope. The position of the mouth mirror is placed on the circumference of the clock according to the position of the hour.
Figure (1) The mouth mirror clock, the center is the co-plane of No. 14
Right-handed operators can start from the 14th tooth. If you operate with the left hand, you can start with the 3rd tooth on the right, and all subsequent operations will choose the opposite quadrant, the opposite tooth, and the mirror clock position opposite to the right hand operation.
For right-handed operators, the teeth on the left are always easier to manipulate than the teeth on the right. Likewise, the teeth on the right are easier for left-handed operators. This is why the dental handpiece blocks the view.
In the practice, prepare the 14th and 3rd teeth with a dental handpiece and a mouth mirror. The model will be fixed on the dental chair, the field of view will be expanded continuously, and the crown edge will be refined. During the training process, the left and right sides of the teeth need to be considered from the operating point of view, rather than the buccal and palatal sides of the model, which is more conducive to perfect preparation. To prepare the teeth from the left side of 14, there are two positions of the mouth mirror to observe the teeth, one position to observe the left side, and the other position to observe the commissure. Observe the side surface at 9 o’clock, observe the joint surface from the vertical direction at 11 o’clock, and the mouth mirror is parallel to the joint surface at 9 o’clock. If the position of the mouth mirror and the magnification are appropriate, this exercise can improve the operation ability. If the preparation of a part of the tooth is completed, move to another position until it is completed.
figure （2）The highlight position shows the 9 o’clock position of No. 14 dental mirror
Figure (3) shows the left side view of No. 14 tooth at 9 o’clock. The center of the mouth mirror should be on the same horizontal plane as the tooth surface of the observed tooth.
Figure (4) shows the microscopic field of view at the same position as Figure (3). This picture is taken from the opposite side, that is, indirect vision. Note the edges of the mouth mirror on the left and right sides of the upper part of the picture.
The position of the mouth mirror at 9 o’clock and 11 o’clock allows the operator to observe the left side, mesial and distal sides of the tooth. It takes 20 minutes to prepare and refine the three sides of the crown of the No. 14 tooth.
Figure (5) The highlighted mouth mirror shows the 11 o’clock position of the 14th tooth. The two different fields of view at this position are shown in the subsequent figures, and the unlit mouth mirror shows the other 3 mouth mirror positions for tooth 14.
Figure (6) The 11-point field of view of the 14th tooth. From the position of the mouth mirror, the long axis of the tooth can be seen downwards, and the maxillofacial of the tooth can be observed.
Figure (7) adjust the microscope to a higher magnification, the field of view in the mouth mirror is limited, but you can see clearer details on the tooth surface.
Figure (8) Comparison of the visual field of the 14th tooth in the 9 o’clock direction with the position of the mouth mirror shown on the right
Figure (9) The field of view at 9 o’clock on the 14th tooth. This image shows the field of view at a higher magnification.
Figure (10) The 11 o’clock position of the mouth mirror of the 14th tooth is compared with the position of the mouth mirror shown on the right
Figure (11) The field of view at 11 o’clock of the No. 14 dental mirror. This figure shows the field of view at a higher magnification.
After getting used to the left side of the 14th tooth, spend another 20 minutes to refine the right side of the tooth. The most suitable observation positions of the mouth mirror on the right are 3 o’clock and 1 o’clock. The 3 o’clock position requires the midline of the mouth mirror to be consistent with the jaw plane. In order to achieve this field of view, the patient needs to lie supine at 0 degrees or minus 10 degrees so that the operator can see the incisal margin of the maxillary anterior teeth. This position is another challenge for right-handed operators, as the dental handpiece will enter the interference port mirror from the right. At the 3 o’clock position, the line of sight is below the dental handpiece and above the incisal margin of the maxillary anterior teeth.
Figure (12) highlights the 3 o’clock position of tooth 14
Figure (13) 3 o’clock position of No. 14 tooth under microscope.
Figure (14) In this position, the dental handpiece will interfere with the observation of the mouth mirror. In order to avoid interference, the line of sight should be lower than the phone and higher than the incisal margin of the maxillary anterior teeth.
At the 1 o’clock position of the 14th tooth, the long axis of the tooth can be seen. As mentioned earlier, the field of view can also be disturbed by the dental handpiece. To solve this problem, the mouth mirror should be placed on top of the dental handpiece and in front or behind the handle of the handpiece. Summarize the positions of these maxillary posterior teeth, and observe the target teeth along a semicircular or square trajectory from 9 o’clock to 11 o’clock, 1 o’clock to 3 o’clock.
Figure (15) The highlighted position shows the 1 o’clock position of the mouth mirror of tooth 14
Figure (16) The long axis of the tooth can be observed at 1 point
Figure (17) There is interference from the handpiece at 1 o’clock. To avoid interference, the mouth mirror should be higher than the handpiece and in front or behind the handle of the handpiece.
Figure (18) 3 o’clock position of No. 14 tooth
Picture (19) No. 14 tooth 3 o’clock position, mouth mirror at the same position as Fig. 18, observation at higher magnification.
Figure (20) 11 o’clock position of No. 14 tooth
Figure （21） The mouth mirror observes the teeth at 1 o’clock
The purpose of this exercise is not to prepare the crown, but to learn and master how to place the mouth mirror in the correct position. With the use of microscopes, the quality of tooth preparation will naturally be improved.
The references for this article are taken from:Rick Schmidt, Martin Boudro, “The Dental Microscope”
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