Dental treatment agents and their medicinal use

Agents, compositions containing said agents and methods are provided for covering and sealing denture injuries, occuring, for instance, in teeth being prepared to form cavities for the reception and adhesion of sealing agents and filling materials, the solid injury dressing being compatible with said filling material. The agents of the invention comprise an inorganic and/or organic cerium salt in aqueous and/or organic solution and application of said agents or compositions can be subsequently supplemented by treatment with a mineralizing solution.

Dentists have the problem of covering and sealing dentine injuries, 
prepared to form cavities for the reception and adhesion of sealing agents 
and filling materials so that the solid injury dressing is compatible with 
the filling. Numerous attempts have already been made in this respect. 
Thus, it has already been disclosed that dentine can be treated with 
mineralizing solutions (Archs. oral. Biol. 17: 1005-1008, 1972: and J. 
Dent. Res. 55: Spec. Issue, D 135, Abstr. 117, 1976). 
However, this process has the disadvantage that significant incorporation 
of more and/or reactive ions is only achieved after at least 30 minutes, 
which means that the process is unsuitable for clinical application. 
It has also been disclosed to use those amphoteric or acid molecules which 
are capable of forming a bond with dentine on the one hand and with 
filling materials on the other hand (J. Dent. Res. 44: 895, 1965; and Br. 
Dent. J. 132: 133, 1972). 
However, these processes have the disadvantage that either the required 
adhesion to the dentine injury very soon decreases because covering layers 
formed are only loosely superposed on the dentine surface, or that in the 
case of subsequent treatments with filling materials which are harmful to 
the pulp, as a result of inadequate imperviousness, the live pulp is not 
sufficiently protected. 
The present invention relates to an agent for use in the treatment of hard 
tooth substance, which agent comprises an inorganic and/or organic cerium 
salt in aqueous and/or organic solution. 
In a further aspect, the present invention provides a hard tooth substance 
treatment pack for use in the treatment of hard tooth substance, which 
pack comprises a first component comprising an agent according to the 
invention, and a second compound comprising a mineralizing solution. 
In another aspect the present invention provides a pharmaceutical 
composition comprising as an active ingredient an agent according to the 
invention in the presence of one or more of a preservative or antiseptic 
agent, a flavouring agent, a surface active agent, a sweetener, a 
thickener, an abrasive agent, a colouring agent and a filler. 
It has now been found that cut dentine can be provided with a compact, 
strongly adhering, impermeable surface layer or can be restructured and 
can thus be prepared for sealing and receiving organic filling materials, 
for example of the Bowen composite type or of the polyacrylic acid type 
and the like, by applying solutions of cerium salts to the dentine injury. 
A particularly impervious surface is obtained if mineralizing solutions are 
additionally applied after the treatment with solutions of cerium salts. 
Cerium salts are inorganic or organic salts of trivalent and quadrivalent 
cerium, for example CeCl.sub.3, Ce(OOCCH.sub.3).sub.3, Ce(SO.sub.4).sub.2, 
cerium acetylacetone, Ce(NH.sub.4)SO.sub.4 and Ce(NO.sub.3).sub.4 and the 
like. Aqueous or organic solutions, e.g. solutions in propyleneglycol, 
polyethyleneglycol and the like, should preferably be of from 0.1 to 30% 
strength, for example, from 1 to 20% strength (wgt/vol). 6% strength 
aqueous solutions, when used alone, or cerous chloride with pH-values of 
4.0 to 5.0 and 6% strength aqueous solutions of cerous acetate with 
pH-values of 5.0 to 8.0 are preferred. Viscosity increasing mucilasos, 
e.g. hydroxyethylcellulose, carboxymethylcellulose and the like may be 
added. 
When the cerium salt treatment of dentine is combined with subsequently 
applied mineralizing solutions mentioned below, solutions of cerium salts 
up to the saturation concentration can be used. 
Various types of mineralizing solutions can be used: 
1. Calcifying solutions, that is to say solutions which contain e.g. 1-4 
millimols of CaHPO.sub.4.2H.sub.2 O [brushite], Ca.sub.3 (PO.sub.4).sub.2 
or Ca(OH).sub.2 per liter, with pH values of from 6.0-8.0. 
2. Fluoride solutions, for example NaF, NH.sub.4 F, SrF.sub.2, FeF.sub.3, 
SnF.sub.2 [Fluoristan] and amine fluorides [e.g. Olaflur, Hetaflur]. 
3. Solutions containing fluoride ions and phosphate ions ("Acidulated 
Phosphate Fluoride", APF), with a fluoride ion content of up to 2%. 
4. Sodium monofluorophosphate (Na.sub.2 PO.sub.3 F), MFP. 
The cerium solutions and mineralizing solutions may be successively applied 
to the dentine injury with the aid of a brush or a cotton pad or swab. The 
action time is usually from 1 to 5 minutes. 
Compared with the known processes initially mentioned, the process 
according to the invention has the great advantage that a solid, 
impermeable hard tooth substance surface is obtained by restructuring. 
This advantageous effect usually occurs already within from 1 to 5 
minutes. 
The process according to the invention can be used for sealing exposed 
regions of the neck of a tooth or exposed dentine from erosion and 
wedge-shaped defects. 
The superiority of the dentine injury treatment by the process according to 
the invention compared with the known processes can be seen from the 
following experiments: 
Experiment 1 
Sealing of dentine injuries in human teeth by a cerous chlorine treatment. 
Two cylindrical cavities, as far as possible of the same size, were each 
made down to the dentine in extracted molars, (which had been stored in 
0.1% strength thymol) using diamond cutters and fissure burs. After 
cleaning with H.sub.2 O.sub.2, pH 7, for 2 minutes, washing out with a 
water spray and drying, each cavity was treated with 6% aqueous 
CeCl.sub.3, pH 4.5-4.9, for 2 minutes and then dried directly with air. 
Thereafter, the teeth were again rinsed under running water and again 
dried with air. 
For the dyestuff permeation experiment, the cavities were filled with 5% 
strength methylene blue and the teeth were centrifuged for 8 minutes at 
2,800 revolutions per minute in order to force the dyestuff through the 
dentine channels towards the pulp by means of the centrifugal force. The 
teeth were halved through the centres of the test cavities and control 
cavities, using a grinder, and were then photographed. The pictures of the 
ground surfaces were enlarged 68 times by a standardised projection 
process and the extent of the penetration of the methylene blue (MB) into 
the dentine under the test cavity and control cavity was measured 
planimetrically in mm.sup.2. For 8 teeth and 16 measured halves of teeth, 
the average dyestuff penetration in the case of the cavities treated with 
6% strength CeCl.sub.3 was 1,64 mm.sup.2 (MB test: MBT), and in the case 
of the control cavities was 7,79 mm.sup.2 (MB control: MBC). The quotient 
MBT:MBC was thus 0.21. 
Experiment II 
Comparison of the sealing of dentine injuries in human teeth by six 
different processes. 
Two cavities were again made per tooth according to the procedure in 
Experiment 1. One dentine cavity in each case was treated, using six 
different processes, whilst the second cavity served as an untreated 
control. 
In the ultrasonic bath used for washing the teeth with ultrasound, the 
energy released warmed 2 liters of water from 20.degree. C. to 
28.8.degree. C. in the course of 30 minutes at an air temperature of 
25.degree. C. In detail, the following processes were used: 
Process 1: Calciumchloride: 2 minutes with 10% strength H.sub.2 O.sub.2, pH 
7, rinse with H.sub.2 O, dry with air, 2 minutes with 4.05% strength 
CaCl.sub.2, pH 4.5, dry with air, rinse with H.sub.2 O, dry with air. 
Process 2: Cerouschloride and after treatment with a mineralizing solution: 
2 minutes with 10% strength H.sub.2 O.sub.2, pH 7, rinse with H.sub.2 O, 
dry with air, 2 minutes with 6% strength CeCl.sub.3, pH 4.9, dry with air, 
4 minutes with a mineralizing solution (0.5 M Na.sub.2 HPO.sub.4 with 
2,000 pp, of F.sup.- in the form of NaF), dry with air, rinse with H.sub.2 
O, dry with air. 
Process 3: (Mineralizing solution alone): 2 minutes with 10% strength 
H.sub.2 O.sub.2, pH 7, rinse with H.sub.2 O, dry with air, 4 minutes with 
a mineralizing solution (0,5 M Na.sub.2 HPO.sub.4 with 2,000 ppm of 
F.sup.- in the form of NaF), dry with air, rinse with H.sub.2 O, dry with 
air. 
Process 4: (Cerouschloride and ultrasonic washing in a water bath): 2 
minutes with 10% strength H.sub.2 O.sub.2, pH 7, rinse with H.sub.2 O, dry 
with air, 2 minutes with 6% strength CeCl.sub.3, pH 4.9, dry with air, 
rinse with H.sub.2 O, dry with air, 5 minutes in an ultrasonic bath, rinse 
with H.sub.2 O, dry with air. 
Process 5: (cavity lacquer): 2 minutes with 10% strength H.sub.2 O.sub.2, 
pH 7, rinse with H.sub.2 O, dry with air, coating with a cavity lacquer of 
polystyrene, calcium fluorophosphate, calcium hydroxide, zinc oxide and 
di-iodide-dithymol, dry with air, rinse with H.sub.2 O, dry with air. 
Process 6: (cavity lacquer and ultrasonic washing in a water bath): 2 
minutes with 10% strength H.sub.2 O.sub.2, pH 7, rinse with H.sub.2 O, dry 
with air, coating with a cavity lacquer consisting of polystyrene, calcium 
fluorophosphate, calcium hydroxide, zinc oxide and di-iodide-dithymol, dry 
with air, rinse with H.sub.2 O, dry with air, 5 minutes in an ultrasonic 
bath, rinse with H.sub.2 O, dry with air. 
The results of the sealing of the dentine injuries by these six processes 
are summarised in the table which follows, in which the methylene blue 
permeation into the dentine, expressed in average values in mm.sup.2 
(planimetry) for the test (MBT) and the control (MBC) and as the quotient 
Q (MBT:MBC) are indicated. 
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Test process 
Control 
Process 
Number of teeth 
mm.sup.2 mm.sup.2 
Q 
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1 5 7816 8220 0.95 
2 10 944 12010 0.08 
3 5 4815 4855 0.99 
4 8 1135 10050 0.11 
5 4 8359 9556 0.88 
6 8 9728 12339 0.79 
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It can thus be seen that quotients Q are obtained by the processes 2 and 4 
according to the invention which are far superior to those which are 
obtained by the known processes. This applies, above all, when a treatment 
with mineralizing solutions is carried out subsequent to the cerium 
treatment. 
Experiment III 
In order to further demonstrate the micromorphological changes in dentine 
induced by treatment with cerium solutions, thin sections of dentine from 
human teeth were treated on one side by the six processes described in 
Experiment II and then analysed optoelectronically. 
If the boundary area between the untreated dentine (control) and the 
dentine treated according to process 2 (test) are viewed when enlarged 
1,950 times, a sharply defined, sealed covering layer which is resistant 
to washing is found on the test side and is lacking on the control side. 
The treatment of the dentine injury with solutions of cerium salts thus 
leads not only to better sealing but also to better adhesion of this 
injury dressing. 
Artificial and natural dentine injuries, for example in regions of the neck 
of a tooth, which are treated by the process according to the invention 
are more impervious, more resistant to acids and to harmful influences of 
filling materials or chemical irritation caused by food than the untreated 
tooth. For these reasons, dentine injuries sealed according to the 
invention provide favourable conditions for further dental measures, for 
example sealing of dentine, filling therapy using the most diverse 
materials, which irritate the pulp, cements which are tolerated by the 
pulp, local treatment of over-sensitivity of exposed necks of teeth, 
wedge-shaped cervical defects and advanced erosions. The agents according 
to the invention are also suitable for self-treatment with 
cerium-containing dabbing solutions, jellies or toothpastes for 
influencing painful necks of teeth.

EXAMPLE 1 
A recent dentine injury which has been cleaned beforehand with hydrogen 
peroxide is coated with a freshly prepared aqueous 6% strength cerous 
chloride solution for 4 minutes with the aid of a brush. The dentine is 
then dried with air. An impermeable layer which is resistant to ultrasonic 
waves and can be detected as in Experiments I and II is obtained on the 
dentine. 
Instead of the cerium chloride solution mentioned, it is also possible to 
use other solutions of cerium salts, for example a 6% strength cerium 
acetate solution. 
EXAMPLE 2 
A recent dentine injury which has been treated, according to Example 1, 
with a 6% strength cerous chloride solution is then coated with a 0.5 
molar KH.sub.2 PO.sub.4 solution, which has been saturated with Ca(H.sub.2 
PO.sub.4).sub.2, for three minutes with the aid of a cotton pad. After 
rinsing, a thick, impervious precipitate layer which can be detected as in 
Experiments II and III is obtained. 
EXAMPLE 3 
A wedge-shaped defect in the neck of a tooth in the region of the root 
cement is cleaned with hydrogen peroxide and sodium hypochlorite and 
dabbed with a freshly prepared aqueous 6% strength solution of cerous 
chloride for three minutes. 
A 0.5 molar Na.sub.2 HPO.sub.4 solution, which contains 2,000 ppm of 
fluoride ions in the form of sodium fluoride, is then brushed on. After 
rinsing, there is a solid layer on the treated area, which is resistant to 
acid, adheres well and can be detected as in Experiments II and III. 
EXAMPLE 4 
Solution for dabbing painful necks of teeth 
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Cerous Chloride 10.0 
Hydroxyethylcellulose 1.0 
Aromatic agents 0.1 
Aqua destillata to 100.0 
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EXAMPLE 5 
Solution for dabbing painful dentine exposed by cavity preparation 
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Cerous chloride 6.0 
Propyleneglycol 2.0 
Polyethyleneglycol 4.5 
Carboxymethylcellulose 1.0 
Methylene chloride 10.0 
Aqua destillata to 100.0 
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EXAMPLE 6 
Toothpaste 
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Cerous chloride 5.0 
Cerous fluoride 0.1 
Cerous oxide 5.0 
Aerosil 200 30.0 
Hydrated aluminium oxide 10.0 
Quartz powder 10.0 
Glycerol 5.0 
Titanium oxide 1.0 
Sodium benzoate 0.5 
Lauryl sulphate 1.0 
Carboxymethylcellulose 2.0 
70 % strength sorbitol solution 
to 100.0 
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