Biconcave elevator
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Novel instrument of tooth extraction.
The chief of this dental clinic has produced a new tool for tooth extraction. It is a safer and more useful tooth extraction tool than conventional tools.
See below.
https://www.sciencedirect.com/science/article/pii/S2667147624000074?via%3Dihub#kwrds0010
When teaching new trainees how to extract teeth, we tell them to use the elevator if the forceps won't work. So, let’s think about whether our teaching of the elevator is logical.
How do we grab it? How do we penetrate it into the periodontal ligament cavity? How do we move it? What principle does work to extract a tooth?
Are they just teaching based on a vague feeling? Grab it like this, penetrate it like this, move it like this, so on.
For new practitioners, the type of medical accident that can occur when using an elevator is known as a stabbing accident.
The key to this type of stabbing accident is whether the tip of the elevator is firmly digging into the periodontal ligament cavity to prevent it from slipping. And even if it is digging in, moving the elevator can cause the fulcrum or force point at the tip of the elevator to overmove from the groove in the periodontal ligament cavity and go beyond the alveolar bone crest.
When a stabbing accident is about to happen, there is one way to prevent it. That is to keep your arms close to your sides and to hold the elevator in a way that a part of your hand will act as a stopper to prevent it from slipping any further.
To do this, you need to place your index finger as close to the tip as possible.
If you place your index finger as close as possible to the tip, the fulcrum or point of force at the tip of the elevator will slip from the groove in the periodontal ligament cavity across the alveolar bone ridge, and if the elevator slips, part of your hand will act as a stopper.
We have developed a new elevator to avoid such stabbing accidents.
Abstract
This presentation introduces a novel elevator that facilitates tooth extraction. The elevator has excellent insertion ability independent of tooth shape, high insertion operability into narrow spaces, and fine force transmission ability. The head of the elevator has a biconcave web structure connecting to two sharp tips. It is easily inserted into a narrow periodontal space and features good tactile sensation without slipping. It allows for reduced extraction times for patients.
Introduction
When tooth extractions using any forceps are challenging, elevators are employed 1. Various types of elevators can be found in the literature 2; however, a generalized form of the commercially available elevators is a so-called “shovel-shaped”. It features a central convex tip in the axial direction, a concave front surface designed to fit the convex tooth root, and a convex back surface that should match the concave alveolar bone. Conventional shovel-shaped elevators have been commonly used in daily dental practice; however, the shape of tooth roots is diverse, the cross-section of the alveolar bone is not always concave, and some convex bone surfaces interfere with the convex backs of the elevators. Some elevators have been developed to be thinner and/or narrower than conventional elevators for easier insertion; however, the disadvantage due to their shape has not been overcome. Here, a new type of elevator for tooth extraction that avoids interference from convex bone surfaces is reported 3.
Fabrication of the instrument
A prototype of a new elevator that has a head consisting of a biconcave web and a bimodal tip is reported (Fig.1). The biconcave web has a large concave surface on the front and a small concave surface on the back in its axial cross-section, which connects two sharp tips and reinforces them. The head looks like two sharp root-tip-type elevators connected by the biconcave web. It has an approximately 20-degree bent neck to insert easily from the mesial or the lateral position, and a small oval concave surface on the front side as one of the best places to rest your index finger.
Fig. 1 Head and neck structure in a rod of the biconcave elevator.
Front view (a), side view (b), rear view (c), cross-section view (d), and front (e) and rear (f) photographs of the biconcave elevator. Black dashed lines indicate virtual planes for cross sections. A blue dashed circle indicates one of comma-shaped pointed tips. Two red dashed arcs indicate the biconcave surfaces of the head. The front has a large concave surface (a, d, e), and the back has a small concave surface (c, d, f). Twin peaks are a secondarily distinctive feature (a, c, d, e, f). Each green arrow indicates an oval concave surface on the front neck of the rod as an optimal rest for an index finger (a, b, d, e). The distance between one tip and another tip is 4-3 mm (a, c, d, e, f). It is bent about 20 degrees at the neck (b).
Use of the instrument
The elevator is used in the same way as conventional elevators. In addition, the space between the two tips and the biconcave web allows it to be used for roots of various sizes and shapes. The two tips can be inserted into any irregular periodontal ligament spaces separately (Fig. 2). Depending on the insertion position, either the front or back side of the head can be used facing the tooth. The head has two lateral ridges that serve as a non-slip fulcrum. As a point of action, either the tip bites into the cementum, and another tip or the lateral ridge of the tip bites into the alveolar bone as a fulcrum. When the force is applied, the power is transmitted without slipping because of the fixed action and fulcrum point. A small oval concave surface on the front side reminds one of the best positions for the index finger. To tell trainees and/or to remind even experienced dentists why this oval concave surface exsists and how to use it help prevent stabbing accidents. As a result, the tooth is extracted quickly and safely, and the stress on the patients is reduced.
Fig. 2 Several ways to insert the elevator into the space between a tooth and a mandibular bone.
A three-dimensional view of a right mandible, the head of the elevator, and a horizontal virtual plane showing a parallelogram (a). An angle formed by two dotted lines indicates the bend between the head and shaft in Fig. 2a. It is approximately 20 degrees. Fig. 2b is a cross-sectional view cut by the virtual plane in Fig. 2a. Fig. 2c is a magnified view of a rectangular area in Fig. 2b. The two comma-shaped black cross sections (p1) in Fig. 2c show the two tips of the elevator shown in Figure 2a inserted into the space with the back side facing the tooth surface. The other two comma-shaped black cross sections (p2, p3, and p4) in Fig. 2d show the other available positions. Even the back side (p1 and p3), as same as the front side (p2 and p4) of the elevator, fits any shape of root. In addition to the usual way, the elevator can be inserted into the distal labial space (p1) or the inner side space (p3) like a reversed carve elevator without interference because of its concave curving and the bend. Each tip can be inserted without interference from the convex root (p1, p2) and the convex bone (p3, p4). It works like two root-tip-type elevators connected.
Discussion
Here we report a new type of elevator that consists of a biconcave web connecting two tips. Compared to the conventional shovel-shaped unimodal elevators, this elevator has three advantages. The first is morphologically independent insertion ability because there is no obstruction of the convex back surface. The second is high insertion operability into narrow spaces because of the sharply pointed tips. The third is excellent force transmission due to the non-slipping effect of the sharply pointed two tips. These features give this new extraction tool the benefits of ease of use, even in difficult situations, and less time in the chair for patients. In addition, it is an excellent tool to educate trainees on how to extract difficult teeth without stabbing accidents by elevators.
Acknowledgments
The author would like to thank Dr. Kiyo Iwashiro, Dr. Takuma Watanabe (Kyoto University), and Dr. Kim Hasenkurug for their encouragement and useful comments.
Reference
1. Colyer JF Extraction of the Teeth. London: Claudius Ash & Sons Limited, 1896
2. Bussel MA, Graham RM The history of commonly used dental elevators. Br Dent J 2008: 205: 505-8
3. Iwashiro M Biconcave elevator: A novel instrument of tooth extraction: A technical note. ADOMS 2024: 100485
Patent: Patents regarding this elevator have been filed with the Japan Patent Office and the USPTO in the USA.
Competing interests: The author declares that he has no conflicts of interest except the patent.
Funding: None. Ethical approval: Not applicable.
Patient Consent: Not applicable.