Optical magnifiers in dental technology
Precision work – this term highlights the quality results expected in dentistry and dental technology for prosthetic restoration. Magnifying spectacles, headband magnifying instruments or stereomicroscope contribute to achieving these quality results. Their magnification enables dental restorations to be fabricated to a high degree of precision. Using these magnification aids the required precision of fit in dental medicine and technology (crown marginal gap accuracy <50µm) comes much closer.
Application
Magnification aids in the form of magnifying spectacles or headband magnifiers can be used to improve vision during manual trimming/polishing of restorations in the dental laboratory. Their magnification factor can be 2.5 to 6 times the actual size of the restoration, depending on the model selected.
The use of stereomicroscopes can be even better, however, as their magnification factors – also depending on the model – are much greater than these values (up to 100x). Like magnifying spectacles or headband magnifiers they can be very easily positioned ergonomically: they generally have spring-joint support and can therefore be easily aligned to the user's working posture.
Function
With stereomicroscopes each eye observes "its image" from its own viewing angle, which is captured by a lens via the respective eyepiece. "The images" are not combined to form a three-dimensional picture until they reach the user's brain.
Viewing the details of the restoration using magnifying spectacles, headband magnifiers or a stereomicroscope is aided by the "reflected light" of the laboratory workstation or cold or LED light (Light-Emitting Diode). These light sources are optionally available for magnifying spectacles and headband magnifiers and are 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.
Options
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 select a low magnification in favour of a larger viewing field.
Duration of use can also be a criterion for selection: if the restoration is to be viewed under magnification during the entire working time, magnifying spectacles or a headband magnifier may be more appropriate. If optically supported observation is only carried out at the final preparation stage or final check, a stereomicroscope may be the correct choice.
When purchasing magnifying spectacles, a headband or stereomicroscope, preparation of a restoration should be simulated using different types of products – for example dental crowns and bridges with a pronounced surface relief are ideal. This also tests the ease of use of the respective product – an important criterion for daily long-term use.
