Dhi Method and Technical Features

Excellent results have emerged with the dhi method that we have been applying since 2009. In recent years, the dhi technique has started to gain momentum rapidly in our country. However, it should not be forgotten that this method is not an application specific to FUE. It has also been successfully applied in FUT hair transplantation for many years. Unfortunately, very few doctors have been able to achieve success with this method. The reason for this is that the pen technique has some tricks and requires detailed technical knowledge. In addition, the fact that the materials used are more expensive has caused this technique to be less known.

In our article called Dhi hair transplantation, we explained this application in detail. The pen method also requires knowing the technical details. What we will explain here are the technical details that the doctor who will perform the application should know. In other words, the conditions required for a successful Dhi result. If the details of this technique are not known correctly, it is possible that incorrect results will occur.

What is the Dhi Method?

As we know, in hair transplantation, grafts are first removed from donor areas. Then these grafts are transplanted to hairless areas. Graft transplantation can be done in several different ways. One of these is the pen hair transplantation method. The device we call implanter has been known since the early 1990s. It resembles a ballpoint pen. It has a spring mechanism inside. A root is placed inside the choi pen. Then the graft is transplanted to the hairless area. Here, channel opening and root placement are not done separately. Channel opening and root placement are done simultaneously. In other words, channels are not opened in advance as in FUE. While a hole is opened, the hair root is also transplanted at the same time.

The real name of this method is the implanter pen technique. In our country, it is known as choi hair transplantation, dhi technique, pen technique. As can be seen, the dhi method has been applied for many years in both FUE and FUT methods.

Pen Types Used in Choi Hair Transplantation

First of all, let’s get brief information about the pens used in the dhi technique. We can first divide the implanters used in hair transplantation into 2 main groups.

a) Sharp Needle Implanter (Sharp Needle Tip)

All of the pens sold in Turkey are in this group. It is applied with the stick and place technique. There are 5 different sharp needle implanters. In fact, all of these brands are of South Korean origin. These pens have the same functions except for some minor details. Except for the fifth one, the others are available in Turkey.

1. Choi Implanter Pen: It is the first type offered for sale in Turkey. Since this brand is the first in Turkey, the dhi technique is also known as the choi hair transplantation technique.
2. KNU Implanter:
3. Lion Implanter Pen : The needle tip slits are a little wider than the others. We think it is more ergonomic and useful than the others.
4. OKT Implanter Pen: It has entered the Turkish market in recent years. Depth control is easier than the first 3 brands.
5. HWANG Implanter: It is the only sharp-tipped implanter with depth control (stopper). It is not available in Turkey. It is sharpened internally and externally. It is the sharpest-tipped implanter. The needle wall thickness is the thinnest. We can say that it is the best in terms of ease of use.

Although there are minor details among these items, their basic working principles are the same.

In the picture above you can see the classic sharp tip implanter and the huwang implanter (with depth control).

b) Dull Needle Implanter (DNI Blunt Tip)

It is not yet sold in Turkey. It has a blunt tip. The needle tip slits are wider. The channels are opened in advance, and then the roots are placed in the opened channels using a pen. We can include the K.E.E.P apparatus designed by Dr. Koray Erdoğan in this group. In fact, it differs from the classic dull needle implanter in some ways. The graft inside the needle is manually placed into the socket with the help of forceps.

Differences Between Sharp and Dull Needle Implanters

There are some differences between Sharp and Dull Needle pencils. We can summarize these differences in the table.

	Sharp Needle Implanter (Sharp Tip)	Dull Needle Implanter (Blunt Tip)
Graft Placement	Stick and place method	Planting is done in pre-drilled holes.
Needle Incision Size	It is the same as the needle size.	It may be smaller than the drilled hole size. For example, 0.8 mm for a 0.9 mm channel.
Density	Determined when roots are placed	Determined before graft placement
Planting Time	Fast	Relatively slower
Needle Tip Change	If three become dull, it must be changed	No need for change
Bleeding and Root Expulsion	Adırz	It’s a little too much.
Needle Slit Diameter	Narrow. Usually 0.2 mm	Wider (Usually 0.35 mm)
Stopper (Depth Control)	It is not available in those other than Hwang Implanter.	There is no such thing.
Advantages / Disadvantages	In long roots, the upper part of the graft should be taken out of the slit. Otherwise, it may be crushed. In thick grafts, there may be damage during placement due to the narrow channel.	Risk of trauma is low

For the sterilization of pens, chemical disinfectant (Saydex) or, if possible, Ethylene Oxide should be preferred. Dry air sterilizers such as autoclaves or ovens can damage the needle structure and sharpness. For this reason, we do not prefer them for sterilization.

Dhi Method and 7 Golden Tips

There are some tricks that have a vital effect on success in hair transplantation with the pen technique. We have brought these tricks in written form after years of experience. We felt obliged to do this for the success of this technique for those who want to have hair transplantation. We found it appropriate to collect these tricks under 7 main headings. Let’s take a brief look at them now.

1- Diameter of Needle Tips

All brands have tips with diameters between 0.6 mm and 1.8 mm on the market. We use 0.6, 0.8 and 1 mm tips in the dhi method. We do not believe that tips larger than 1 mm will contribute to sufficient density and natural appearance in the dhi method. If we list the usage of these needle diameters,

• 0.6 mm: Generally used for eyebrow transplantation and single grafts on very fine hair.
• 0.8 mm: Used for 1 and 2 hair follicles.
• 1 mm: We use it for 2-3-4 multiple grafts.

The diameters of the needle tip may vary depending on the manufacturing company. There are green, red, blue and pink colors on the top of the pens. These colors make it easier for us to distinguish between diameters.

Below you can see examples of sharp-tipped hair transplantation pens available in our country. The diameters of the tips are 0.6, 0.8 and 1 mm.

Suppliers produce tips up to 1.8 mm. In our opinion, tips wider than 1 mm are not suitable for the FUE method.

With an average choi pen, 700-1000 grafts can be transplanted. This number generally varies from person to person. The elasticity of the skin is important here. If the pen causes excessive rooting when inserted during transplantation, the tip should be changed.

2- Width of Implanter Pen Diameters

In very narrow ends, there is a possibility that the hair follicles will be damaged while being placed in the implanter. In case of excessive width, there is a possibility that the placed graft will fall out before the transplantation process is completed. The slit widths vary between 0.2 mm and 0.35 mm.

In the picture below, you can see the high-resolution magnifications of 1 mm diameter needle tips from 3 different companies. The slit width of the needle tip number 1 is wider. The gripping area of ​​the hair root inside the needle, called the Bevel, is wider than the others. We think this situation is advantageous in terms of graft health. Of course, it would not be right to explain these dhi pen brands here.

3- Pen Needle Length

Depth control is one of the most important issues in root placement. Some implanters have depth control. First of all, the pencil length should be reviewed in advance according to the root length.

The standard length of the pen needle is around 7 mm. This length is reduced or increased according to the hair graft length. If there is more bleeding than expected, it means the length is too much. This length should be shortened. When we reduce the 7 mm needle length to 6.5 or 6 mm, we can see that the bleeding will decrease significantly. If we shorten the length more than necessary, the grafts will not reach sufficient depth. This time, the probability of the grafts coming out will increase. Those planted at a depth greater than normal will either not come out or will cause a curly appearance.

A mathematical proportion should be established between the needle length and the graft length. This length should be 25-30% longer than the graft length. For example;

Graft Length: -> Needle Length:

• If it is 6 mm -> Length is 8 mm (25% increase)
• If it is 5 mm -> Length is 7 mm
• If it is 4 mm -> Length should be 6 mm (33% increase).

If the doctor is experienced, she can easily adjust this ratio after a few tries.

4- Length of the Filament That Pushes the Hair Roots Under the Skin

This wire should definitely not protrude from the tip of the teflon spiral. If this wire protrudes when pressed from the top and is visible from the outside, it means that the application is wrong. It does not touch the top of the hair roots, but directly the root. And this means damaging the hair root. This wire should definitely not be visible from the outside. It should not be too high either. It should be at the level of the teflon protector. We can easily see this when we look at the picture below.

5- Placement of the Implanter in the Skin and Depth of Entry

This is not a problem in implanters with stoppers (depth control). In those without depth control, the needle should never be inserted into the skin until it reaches the end. It should be stopped and its entry into the skin should be stopped when it is approximately 1 mm from the skin. Otherwise, it will be inserted deeper than normal. This is a situation that is gained over time and requires experience. While the insertion process is being carried out, it is necessary to simultaneously remove the pen from the skin. As far as we know, there is no depth control in the DHI method devices available in our country. Let’s not forget that the possibility of a graft inserted deeper than necessary is low.

The possibilities that may arise when grafts are placed too deep are as follows.

1. Folliculitis and Cyst: Small inflammations and oil glands called cysts may form at the hair roots.
2. Hair growing curly
3. Pit-shaped marks at the roots of the hair
4. Increased bleeding during surgery
5. Decrease in hair growth percentage

As can be seen; correct depth control in the dhi method is one of the most important stages of the operation.

6. Direction of the Needle Tip When Placing a Graft

According to our experience, the pen’s slit part facing down (i.e. facing the skin) increases the probability of success. In this way, while the sharp part of the needle is inserted into the skin, its angle is simultaneously made horizontal. Thus, the required depth of planting is done in a controlled manner. When inserted at a horizontal angle, full harmony is achieved with the fat tissue and capillary tissue where the hair graft will be combined. In scarred areas and vertex region, inserting the pen by turning it will be advantageous in terms of depth control.

7. Stretching the Skin

When the pen technique is applied, pressure will be created as a result of the insertion of the implanter pen needle. With this pressure, it is possible for other hair grafts placed to pop. In order to minimize this situation, other assistant personnel next to the doctor stretch the scalp during the transplant. The assistant personnel stretches the skin from the front, while the doctor stretches the skin from the back of the transplanted area. Stretching is even more important especially in transplants made to the front areas. In addition, the angle of entry of the grafts is reduced even more with the stretching performed. And it allows for horizontal DHI hair transplantation.