Optical magnifiers in dental medicine
Good visibility of the treatment site is indispensible in all dental disciplines if high-quality results are to be achieved. Magnifying spectacles, headband magnifying instruments or a stereomicroscope should therefore be included in the instrumentarium of all treatments in which a high degree of detail precision is required.
In dental treatment visibility is improved by the use of optical magnification aids: magnifying spectacles or headband magnifiers enlarge the treatment site by a factor of 2.5 to 6 times the size of the actual object, depending on the model selected. If a much higher magnification factor is required (up to 100x), the use of a stereomicroscope is recommended.
Magnifying spectacles and headband magnifiers can very easily be ergonomically positioned via spectacle frames or a headband. In the case of stereomicroscopes this is achieved using a spring-joint support, which users set according to their working posture.
Function of stereomicroscopes
With stereomicroscopes each eye observes "its image" from its own viewing angle, which is captured by a lens via the respective eyepiece. The user's brain then combines "these images" to a three-dimensional spatial picture.
Viewing the details of the restoration using magnifying spectacles, headband magnifiers or a stereomicroscope is aided by the "reflected light" of the dental lamp or cold/LED light (Light-Emitting Diode). These light sources are optionally available for magnifying spectacles and headband magnifiers and are generally integrated in stereomicroscopes. They illuminate the work area so well – assuming good quality products adjusted correctly to be shadow-free – that the user can work for a long time without suffering eye fatigue.
When choosing magnifying spectacles, headband magnifiers or stereomicroscopes it is essential to note: with identical magnification (e.g. 2.5x) the viewing field expands in proportion to increases in the working distance. But: with an identical working distance the viewing field reduces. The greater the magnification – from 2.5x over 3.5x, 4x, 5x to 6x – the more the section of the working area which can be viewed shrinks.
For this reason the user should consider very carefully for which purpose the purchase will be used and if maximum magnification is necessary for each case. It can sometimes be practical to assess the magnification factor according to the area of use: a small viewing field, for example with endodontic or implantological treatment and a large viewing field with low magnification for prosthetic treatment.
Duration of observation can also be a criterion for selection. With magnifying spectacles or headband magnifiers the viewing field changes with every movement of the head – and even if it is only very minimum. With a stereomicroscope that has already been focussed, however, the viewing field remains identical over the entire duration of treatment – until the microscope is realigned. And the extra visual options of this optical magnification aid may also interest the operator, such as transmission of the viewing field to a monitor or the recording of treatment to a data carrier. The better illumination of the treatment site could also be a decisive factor for product selection in comparison with magnifying spectacles or headband magnifiers.
When purchasing magnifying spectacles, headband magnifiers or a stereomicroscope it is always recommended to try out the prospective product chairside. This allows the working distance and individual treatment position to be authentically combined and the "correct" combination of magnification factor and viewing field to be selected. This also tests the comfort of the respective product – an important criterion for daily long-term use.