Digital intra-oral imaging made simple: part two

During the 10 years that I have been working in the digital X-ray market there have been many changes in the products that are available. The market moves so quickly that it is sometimes difficult to keep abreast of the changes and to decide which new features are useful and which are not.

Different types for different people

There are two different types of digital X-ray systems: direct and indirect. Direct is either CCD-based or CMOS, while indirect are normally phosphors plate systems. Below I will go through the advantages and disadvantages of both systems, although some makes may differ so take this as a starting point to making your decision.



• Instant imaging (range from two to 10 seconds)

• Direct connection to your computer

• High resolution (range from 15lp/mm to 20lp/mm)

• Sensors can be swapped between surgeries

• Robust build.


• Sensors not flexible (difficulty in positioning)

• Change in positioning technique required

• Expensive to replace if damaged

• Expensive to digitalise large practices

• Not a full range of sizes (only 0, 1, 2)

• True bitewings are near impossible to achieve in all patients

• Children are difficult to position.



• Easy positioning

• Full range of sizes (0, 1, 2, 3, 4)

• Short learning curve

• Ideal for bitewings and children

• Plates are flexible

• Cheap to replace if damaged.


• The nurse has to leave room to develop X-rays (unit normally centrally based)

• Normally low resolution (9lp/mm to 20lp/mm)

• More steps, therefore increased chance of errors

• Plates can be damaged easily by scratching

• Plates will need to be replaced within one to two years due to wear

• Flexible plates may cause distortion if RINN Positioning is not used.


Check you current set-up:

1. X-ray equipment – if you have an OPT, can it be digitalised?

2. Check the spec of any computer equipment you already have.

The next step

Having looked at the advantages and disadvantages are you still none the wiser? Generally, large practices choose indirect systems because:

1. It is cheaper to digitalise a large practice with indirect

2. Better acceptance from associates; remember them when making your decision

3. They treat a lot of children and carry out bitewings, and the indirect system is easier to position.

Specialists normally go with direct systems because:

1. They need instant imaging

2. They do an increased number of PAs and fewer bitewings

3. They do not treat many children.

Note that practices differ in their needs and that the above is a generalisation.


Which system is best for you? It simply depends on who you are, what equipment you have and where you see you practice going in the future. There is no wrong system, but rather one that works for you, suits your practice and its needs. Check the things that I have mentioned in this article and you will be on track to the right solution.

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