Treatment chamber for the photopolymerization of dental plastics

A treatment chamber as an accessory device for an illuminator for the photopolymerization of dental plastics. The chamber is both light-tight and has at least one movable chamber wall. A light conductor is provided for the light input.

FIELD OF THE INVENTION 
The invention relates to a treatment chamber used as an accessory device 
for an illuminator for the photopolymerization of dental plastics such as 
methacrylic resins. In particular, the chamber has interior walls which 
are light reflective, an opening on one wall to transmit light into the 
interior of the chamber, a light trap and a terminal for a light 
conductor. 
BACKGROUND OF THE INVENTION 
A treatment chamber is disclosed in GB patent No. 1,485,908 which is used 
for the heating of solder by radiation produced in an illuminator and 
delivered by means of a light conductor to the interior of the treatment 
chamber. The treatment chamber is provided with a loading slot for the 
insertion of the material to be treated into the interior of the chamber. 
The device is not useful as a treatment chamber for photopolymerization of 
dental plastics because some light will emit through the loading slot. 
This will result in an unsymmetrical irradiation of the dental plastics 
and cause incomplete curing or hardening of the plastics. 
It is the object of this invention to construct a treatment chamber that is 
universally usable in the field of dental technology in which materials 
are treated with light, especially useful for the treatment by 
photopolymerization of articles made from dental plastics. 
SUMMARY OF THE INVENTION 
This object is achieved by the inventive treatment chamber having light 
reflective interior walls which is light-tight or impenetrable to exterior 
light, and by having at least one of the walls defining the chamber as a 
sliding wall or a hinged wall. 
The inventive treatment chamber has the advantage that no harmful light can 
reach the eyes of the operator. This is especially important when dental 
plastics are photopolymerized in the treatment chamber using light in the 
short-wavelength visible range of the spectrum (i.e. 400-500 nanometers) 
and/or from the ultraviolet spectral range (i.e. 320-400 microns). At the 
same time, however, the interior of the chamber remains easily accessible 
for loading with the material to be treated. 
In a first preferred embodiment of the treatment chamber, the wall forming 
the floor of the chamber and the wall containing the opening for the input 
of light are stationary with respect to the other walls. 
In a second preferred embodiment of the treatment chamber the chamber floor 
is movable with respect to the wall containing the opening for the input 
of light. 
To assure that the chamber will not leak light to the outside, it has been 
found advantageous in all embodiments of these treatment chambers to 
provide the edges of the fixed walls with a light trap to be engaged by 
the edges of the movable walls. The light trap is advantageously in the 
form of grooves, in the form of at least one rib, or in the form of 
sealing flanges. A filter is also preferably used to reflect or absorb 
light having a wavelength which is longer than 500 nanometers. 
The light input or "light" used for the photopolymerization of dental 
plastics is preferably in the light spectral range of from 350-500 microns 
and is provided to the treatment chamber by means of a light conductor, 
which can be in the form, for example, of a liquid light conductor, a 
fiber light conductor or a quartz glass rod. The light conductor is 
attached to the treatment chamber at the opening by means of a light 
conductor socket which is disposed on the outside of the chamber wall 
containing the opening for the input of light. One end of the light 
conductor extends into the light conductor socket at a point close to the 
opening in the chamber wall. The other, free end of the light conductor is 
inserted into the terminal provided in the illuminator when the treatment 
chamber is in the operating state. 
Between the end of the light conductor disposed in the light conductor 
socket and the opening in the chamber wall at least one light filter or 
diaphragm may be introduced into the beam path. In the preferred 
embodiment a slide is provided to extend through the light conductor 
socket and carry the filter. By means of light filters of different 
spectral admittance it is possible to adapt the light to different thermal 
and spectral sensitivities of the dental plastics to be photopolymerized. 
Also, the slide can be used for blocking the entrance of light into the 
treatment chamber, especially when material to be treated is introduced 
into the treatment chamber or treated material is removed therefrom, 
without the necessity of shutting off the light source in the illuminator 
or drawing the light conductor out of the socket provided on the 
illuminator. 
Preferably, a viewing window can be inserted in either a side wall of the 
chamber or in the chamber top, and the viewing window may be provided with 
a light-reflective coating on its surface facing the chamber interior. 
This coating may be, for example, a vapor-deposited interference mirror 
which reflects the short-wavelength part of the radiation (e.g. shorter 
than 400 nanometers) used to photopolymerize the dental plastics, such as 
methacrylic resins, but transmits the longer-wavelength radiation in the 
visible range (e.g. 400-500 nanometers). It is thus possible to observe 
the material during its treatment. 
The objects discussed in the foregoing and additional objects which will be 
apparent to those skilled in the art are achieved by the inventive 
accessory for an illuminator used to harden plastic dental filling used in 
the mouth. The accessory may also be in the form of a hand unit which can 
easily be coupled to such an illuminator and permits a great number of 
dental technology operations without the procurement of a complex 
apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The accessory device shown in FIG. 1 has a chamber on whose wall 2 a socket 
3 for a light conductor 4 is disposed. The light conductor 4 consists of a 
fiber core 5 which is surrounded by a stiffening sleeve 6, preferably of 
aluminum. The stiffening sleeve 6 is preferably provided on one end facing 
the chamber 1 with an annular groove 7 which is engaged by a spring 
element 8 or an adjusting screw of the socket 3, so that he stiffening 
sleeve 6 is locked in the socket 3. Any other suitable engaging means 
known in the art may be employed. 
The other end 9 of the light conductor facing away from the chamber 1 may 
be connected to an illuminator for the photopolymerization of dental 
plastics, whose radiation source 10 may be in the form of a lamp with a 
reflector as indicated in FIG. 1. 
The accessory device is preferably a cantilevered unit, so that the 
stiffening sleeve 6 not only protects the fiber core 5 but serves at the 
same time as an arm to support the chamber 1. If desired, feet (not shown) 
may be disposed on the bottom 11 of the chamber 1 on which the chamber to 
stand the chamber 1 on a work platform. 
The chamber 1 has a hood 13 which hinges about a horizontal axis 12 formed 
by the chamber roof 14 and the wall 15 which is situated opposite the back 
wall 2 having the opening 17 through which light from the light conductor 
4 is emitted into the chamber 1. The hinge axis 12 of the hood 13 runs 
along the upper edge of the back wall 2. The side walls 18 directly 
adjoining the back wall 2 can either be fixedly joined to the back wall 2 
and the bottom 11 of the chamber 1 or, as indicated in phantom lines 19 in 
FIG. 1, be hinged to the back wall 2 to form side walls of the hood 13. 
The hinged embodiment (i.e. shown in phantom lines) offers the advantage 
that the area in front of the opening 17 for the input of light is freely 
accessible for loading the chamber 1 with a plastic part 20 to be 
irradiated. The part 20 is preferably held on a holder or support 21. 
All of the chamber walls 2, 15 and 18 as well as the bottom 11 and the roof 
14 of the chamber are preferably clad with a light-reflecting material 22 
to form a reflector. If the chamber walls are made of a metal material, 
they preferably have a polished inside surface so that the entire interior 
of the chamber forms a reflector. It may be appreciated that at least the 
chamber roof 14 and the wall 15 opposite the opening 17 may bulge in a 
convex shape in order to focus the radiation at the approximate center of 
the chamber 1 in which the plastic part is positioned. 
As shown especially in FIG. 2, a viewing window 23 is inserted into the 
chamber roof 14, and has on its interior surface facing the interior of 
the chamber a reflective covering 24. This reflective covering 24 can be, 
for example, a mirrored material which on the one hand reflects the 
radiation in the interior of the chamber 1, and on the other hand is 
transparent from the outside of the chamber 1, so that an operator may 
check the plastic part 20 for correct positioning during operation of the 
device. 
A slide 25 may also be provided between the socket 3 of the light conductor 
4 and the back wall 2, as shown in FIG. 2. Such a slide may have a 
diaphragm, not shown, or one or more filters inserted into it, and is 
preferably displaced in the direction of the arrow 26 in order to position 
the filter or the diaphragm in front of the opening 17 in the wall 2. 
While the accessory device illustrated in FIGS. 1 and 2 is a cantilevered 
unit, the accessory device may also be built as a free-standing unit, such 
as the units illustrated in FIGS. 3 an 4. 
The free-standing units have a housing 27 on top of which the chamber 1 is 
placed. The floor 11 of the chamber 1 may simultaneously form the roof of 
the housing 27. Feet (not shown) may be provided. On the bottom of the 
housing 27, which may be backed out of the bottom plate so as to set the 
hood 13 at different heights above a work table, so that the position of 
the socket 3 of the light conductor 4 can be adjusted to the position of 
the socket of an illuminator. In this free-standing unit a timing relay is 
inserted into the housing 27, with an operating dial 28 on the rely front, 
by which the irradiation time can be set. In a preferred embodiment, a 
receptacle for the power supply of the illuminator is disposed on the back 
of the housing 27, so that the delivery of power to the illuminator will 
be interrupted by the timing relay at the end of the required irradiation 
time. 
In contrast to the embodiment according to FIG. 1 and FIG. 2, the hood 13 
as illustrated in FIG. 3 is preferably held on an articulation on the 
front edge 29 of the floor 11, indicated by the axis of rotation 12 in the 
direction of the arrow 30. In the open position the hood 13 lies against 
an abutment so that the opening angle will be limited to the position of 
the hood 13 shown in FIG. 3. The hood in this case is made up of the 
chamber roof 14 with the viewing window 23, the two lateral walls 18, and 
the front wall 15. In the opening position the interior of the chamber is 
freely accessible from three sides. 
In another preferred embodiment, the hood 13 of the chamber 1 may be 
disposed so as to slide on tracks 31 on the housing 27 to thus open and 
close the chamber, as illustrated in FIG. 4. A good guidance of the hood 
13 is assured by the fact that the housing 27 is made longer than the 
embodiment according to FIG. 3, so that when the hood is open it lies on 
the tracks 31. 
The tracks 31 which cradle the edge of the hood 13 or wrap around it (see 
FIG. 6) form at the same time a light trap which assures that no light 
harmful to the eyes of the operator will reach the exterior from the 
inside of the chamber. In order to seal all of the edge of the hood 
against the escape of light, sealing flanges or ribs 32 are associated 
with those edges of the hood 13 which are not guided by a track 31, as 
indicated at the front edge of the floor 11 in FIG. 1 and represented in 
FIG. 5. These sealing flanges or ribs 32 are situated preferably on the 
walls of chamber 1 which belong to the hood 13 which are not hinged. 
It will be understood that the specification is illustrative but not 
limitative of the present invention in that other embodiments within the 
spirit and scope of the invention will suggest themselves to those skilled 
in the art.