'Chuck' is not just a 'boorkop', but a specific part of the 'boorkop' that is used for attaching drills, bits etc. I'm not quite sure, but I think that in case you could render 'push chuck' as 'drukkoppeling' or perhaps 'snelkoppeling' in Dutch. See the reference below for a description of pneumatic screwdriver that seems to be equipped with such a device. Heaven forbid that your dentist uses such a thing, but as an illustration it may be of help here ;-)

PS: The site also mentions a 'snelwisselhouder', which could also refer to the chuck.

http://www.overtoom.nl/is-bin/INTERSHOP.enfinity/eCS/OIN/nl_...

Pneumatische schroevendraaier 4700
> Optimale veiligheid
> Lage aanschafkosten
> Duurzaam in gebruik
> Ergonomisch vormgegeven
> Werkdruk 5-8 bar
> Luchtaansluiting 1⁄4"

Pistoolmodel met **drukkoppeling** en instelbaar draaimoment. Met links⁄rechts-omkeer. **Snelwisselhouder** met 1⁄4'' opname.

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Note added at 5 hrs (2006-08-17 09:40:00 GMT)
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errata: 1. but I think that in **this** case; 2. a description of **a** pneumatic screwdriver

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Note added at 5 hrs (2006-08-17 09:57:20 GMT)
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In the reference below, the term 'drukknop spantang' is used. To mind mind, this could also refer to a push chuck mechanisme. Once again, I'm not sure. Hope this helps!

http://www.dentalparts.nl/KaVo_Multiflex_LUX_turbine_hoekstu...