Non-aqueous dental cements based on dimer and trimer acids

Non-aqueous polycarboxylic acids such as dimer and trimer acids are reacted with a variety of polyvalent metal bases to yield a new, versatile class of cements. Many of these cements have unique energy-absorbing properties and excellent dimensional stability yielding mechanically tough and ductile materials. They also do not inhibit the polymerization of resin-based dental materials and thus can be formulated to yield hybrid resin-composite-cement materials. The bulky, hydrophobic nature of these acids with their relatively low carboxylic content results in cements that are low shrinking, hydrolytically resistant and biocompatible.

BACKGROUND OF THE INVENTION 
This invention relates generally to dental compositions and more 
particularly to dental cements based on dimer and trimer acids. 
Researchers, in a quest for a non-eugenol cement, have demonstrated the 
ability of many non-chelating, monocarboxylic acids in a liquified state 
to form coherent, cementitious products on admixture with divalent metal 
oxides or hydroxides. The matrix of these monocarboxylate cements probably 
consists of a loose association of the divalent metallic carboxylate salt 
which, depending on the nature of the carboxylate anion, may have resinous 
or amorphous qualities (FIG. 1). Relatively high molecular weight 
monobasic acids yielded cements of low solubility and water-repellancy. 
However, probably because of the nature of the binder, these cements were 
mechanically weak, especially after exposure to water at 37.degree. C. 
By contrast, the conventional polycarboxylate-based cements (i.e. zinc 
polycarboxylate and glass ionomer cements) derived from aqueous solutions 
of poly(alkenoic) acids and basic inorganic powders with leachable 
polyvalent cations, are much stronger materials. The matrices of these 
cements, which contain considerable amounts of water, are formed primarily 
by a series of ionic cross-linking reactions involving the pendant 
carboxyl groups of the polyelectrolyte and polyvalent cations displaced 
from the base powder by the acid solution. The resulting polymeric binders 
are relatively rigid and hydrophilic, i.e. they are stiff hydrogels (FIG. 
2). 
In U.S. Pat. Nos. 3,837,865 and 4,161,410, both to Pellico, a C.sub.36 
dimer acid or a C.sub.54 trimer acid is mixed with zinc oxide or a mixture 
of zinc oxide and MgO to produce a dental composition. Powder to liquid 
ratios of up to 4 are disclosed. Because of these low powder to liquid 
ratios (P/L), the substances were somewhat flexible and not suitable for 
all dental cement applications. At higher P/L ratios, brittle fracture was 
expected. Furthermore, the compositions of Pellico and most dental 
compositions tend to contract upon setting. This contraction present 
serious difficulties when the cement is intended for many dental 
applications. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a strong dental cement 
which does not undergo brittle fracture. 
It is another object of the present invention to provide a dental cement 
which is hydrophobic. 
It is a further object of the present invention to provide a dental cement 
which is less ionic, hydrophobic, and resistant to deformation under 
compression and brittle fracture. 
It is yet another object of the present invention is to develop useful 
cements having polymeric matrices of much less rigidity and hydrophilicity 
than prior art dental cements by acid-base, chain-extending reactions of 
dimer (DA) and trimer (TA) acids with a variety of polyvalent bases. 
These and other objects are achieved by the reaction product of dimer 
and/or trimer carboxylic acids with a select group of bases and/reactive 
and non-reactive fillers. The reaction may be carried out at ambient 
temperatures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferably, the dental composite formulation comprises the reaction product 
of a dimer and/or trimer carboxylic acid and a base and/or filler. 
The base and/or filler (i.e., the powder component) may be SrO or binary 
mixtures of ZnO and ZrO.sub.2, ZnO and CaSiO.sub.3 ; ZnO and ethylene 
acrylic acid copolymer 5 (PEAA), Ca(OH).sub.2 and tribasic calcium 
phosphate; Ca(OH).sub.2 and MgO; Ca(OH).sub.2 and TiO.sub.2, Ca(OH).sub.2 
and ZnO, ZnO and TiO.sub.2, Ca(OH).sub.2 and SrO, ZnO and SrO, or ZnO and 
Al.sub.2 O.sub.3. If ZnO is used, the powder is preferably micronized. All 
percentages and ratios referred to herein are by weight, unless otherwise 
stated. Additional fillers may be included in the mixtures used. 
For both binary and ternary powder components, a wide range of compositions 
and powder-liquid ratios may be used. As more of the powder component 
comprises a powder of a small volume-weight ratio, such as ZnO, a greater 
P/L ratio may be employed. For example, with a 10% Ca(OH).sub.2 -90% ZnO 
powder component, a P/L ratio of 7 may be used. 
A ternary powder component comprising Ca(OH).sub.2, MgO and ZnO may also be 
employed, with excellent results. If a ternary, rather than binary, powder 
component is used, then a P/L ratio of from between 1 and 8 and preferably 
between 1 and 9 should be used. The actual P/L ratio used is dependent 
upon the amounts Ca(OH).sub.2 and ZnO present. Higher P/L ratios may be 
used depending upon the amounts of Ca(OH).sub.2 and ZnO used. In general, 
larger percentages of Ca(OH).sub.2 require the use of a lower P/L ratio, 
while larger percentages of ZnO allow the use of a higher P/L ratio. In 
general, for any one powder, higher P/L ratios decrease the tendancy of 
the composition to contract upon setting. 
Additional fillers may be included within the unitary, binary or ternary 
powder component. 
Preferably, when a ZnO-containing powder (except when mixed with PEAA or 
Ca(OH).sub.2) is used, ZnO is about 20-90 weight percent of the powder, 
and a powder to liquid ratio of greater than 4, and preferably at least 5, 
up to at least 10, is used. When ZnO is mixed with PEAA in a powder, ZnO 
should be about 92-80 weight percent of the powder. The use of PEAA as a 
filler does not significantly affect the preferred powder/liquid (P/L) 
ratio. 
The dimer acids are C.sub.36 dimer acids and the trimer acids are C.sub.54 
acids. These acids are formed by joined units of C.sub.18 acids. 
The powder and the acids used may be mixed as a powder-liquid or as a 
powder-paste with similar results. The powder-liquid ratios discussed 
refer to the total amount of powder present, whether first mixed with 
liquid (i.e. dimer or trimer acid) or not. Obviously, only non-reactive 
fillers may be used to form a paste from the liquid. For the sake of 
convenience, the term "powder component" refers to all powder present, 
reactive and non-reactive, whether a portion thereof is mixed with liquid 
or not. 
Ca(OH).sub.2 may be made less reactive by heating, to increase setting 
times to workable limits. When this deactivated Ca(OH).sub.2 is used, a 
larger percent of Ca(OH).sub.2 may be present in the powder component 
without so shortening the setting time that the powder becomes unworkable. 
MATERIALS AND METHODS 
I. Materials 
A. Liquid Polyacids 
Dimer (DA) and trimer (TA) acids are designations for the moderately 
viscous, liquid products obtainable from the polymerization of certain 
unsaturated C.sub.18 fatty acids (e.g. oleic, linoleic, etc.). The exact 
chemical structures of DA and TA are somewhat uncertain as they each 
consist of complex isomeric mixtures of C.sub.36 diacids and C.sub.54 
triacids. Some 3. Schematic structures of DA and TA are shown in FIG. 4 
where the R groups are alkyl side chains. The unique properties of these 
polyacids, such as their room temperature, workable liquidity and their 
bulky flexible hydrophobic core structures terminating in 2 or 3 carboxyl 
groups, suggested their use as the acid component of this new type of 
cement. 
For this study the purest grade of a commercially available DA was used 
(1010 Empol dimer acid, Emery Industry, Inc., Cincinnati, OH). This grade 
of DA has 97% DA and 3% TA and extremely low redisual unsaturation. The TA 
used was a grade that consisted of 90% TA and 10% DA (Empol 1041). The 
average molecular weights were 565 and 850 for DA and TA, respectively. 
B. Base Powders 
The base powders used in this study are listed in Table A with their names, 
chemical formulas, grades and sources. Some of the base powders (CaO, MgO, 
ZnO) of reagent grade required activation by ball milling and/or exposure 
to small amounts of certain carboxylic acids (e.g. acetic, propionic). 
Typical procedures for these surface treatments of the bases are outlined 
below. 
ACTIVATION BY BALL MILLING 
Reagent grade CaO and MgO were activated by centrigual ball milling in 
ethanol for 24 and 48 h, respectively. (Pulverisette 6, Tekmar, 
Cincinnati, OH. 
ACTIVATION BY ACID PRETREATMENT 
The various reagent grade oxides (CaO, ZnO, MgO) were activated by surface 
treatment of these powders with organic solvents such as hexane, 
cyclohexane, dichloromethane, acetone, etc., which contained small amounts 
(e.g. 0.5-2.0%) of monobasic acids such as acetic, proprionic acid, etc. 
After mixing in a flask for 15 mins., the solvent was removed by simple 
rotary evaporation procedures. 
C. Fillers 
The fillers used in this study are listed in Table B with their names, 
chemical formulas or acronyms, grades and sources. 
D. Cement Evaluations 
The setting times, compressive strengths, and, in some cases, the 
solubilities of the new cements were determined according to the 
respective tests of ANSI/ADA Specification No. 30 for Dental zinc 
Oxide-Eugenol Type Restorative Materials. The diametral tensile strengths 
of cylindrical specimens, 6 mm .times.12 mm, were measured with a 
universal testing machine at a loading rate of 5 mm/min. In a few cases 
the 24 h solubility of the cement was determined in 1 M lactic acid 
(neutralized to pH =4). 
RESULTS 
The results are summarized in Tables 1-5. 
SETTING CHARCTERISTICS 
The reactivity of DA and TA with solid metallic hydroxides, oxides and 
other solid basic reactants is dependent on a number of factors: the 
inherent basicity of the powder; its state of subdivision and the type and 
degree of surface activation or modification. Of all the bases studied, 
Ca(OH).sub.2 appeared to be the most reactive, especially thinlayer 
chromatographic grades. Other grades of Ca(OH).sub.2 were not quite as 
reactive but could be made so by ball-milling techniques. 
The order of increasing reactivity of DA with reagent grade oxides as 
measured by setting determinations was CaO&gt;MgO&gt;ZnO&gt;&gt;&gt;Al.sub.2 O.sub.3. The 
first two oxides could be activated by ball milling in ethanol to give 
base powders having acceptable setting characteristics. Surface activation 
by means of acetic acid, propionic acid and other carboxylic acids also 
was effective. With the reagent grade ZnO ball milling in ethanol for 48 h 
did not activate the powder sufficiently to obtain acceptable setting 
times. Activation with 0.5 to 2.0% by weight of propionic acid resulted in 
powders having acceptable setting characteristics. A commercial micronized 
ZnO was a very acceptable base powder, undoubtedly because of its fine 
particle size. Coating reagent grade MgO with ascorbic acid or ascorbyl 
palmitate also seems to have an activating effect on this oxide. Although 
setting times were considerably reduced (e.g. from 4.5 h to 35 mins.) for 
mixtures of these coated oxides and DA, even shorter setting times (e.g. 6 
mins.) resulted from an acetate or proprionate coating on the oxide. 
However, using mixtures of ascorbyl palmitate and propionic acid coated 
MgO with DA gave cement mixes with acceptable setting times. Other 
techniques for accelerating the setting behavior of DA and TA cements 
include the use of mixed base systems (e.g. MgO+Ca(OH).sub.2), and the 
addition of activators to the polybasic acids, e.g. propionic acid, 
2-ethoxybenzoic acid, etc. 
MECHANICAL PROPERTIES 
Table I summarizes the properties of some DA/ZnO cements using ZnO as a 
major basic component. Formulation A using micronized ZnO resulted in a 
tough, strong cement with compressive (CS) and a diametral tensile 
strength values of about 50 and 7 MPa, respectively. Although these 
cements did break in compression at a crosshead speed of 1 mm/min., the 
fracture was more ductile in nature than brittle. Formulations D-G did not 
fragment under this compressive stress unless the time of stress was 
unduly prolonged. At higher crosshead speeds the specimens did fracture 
and, as expected, higher CS was obtained. For specimens that did not 
fracture the value of CS was derived from the maximum stress value 
recorded by the testing machine. In tension, all specimens of the DA/ZnO 
cement fractured cleanly into two halves. 
Some of the properties of DA cements prepared with Ca(OH).sub.2 as the 
basic component are shown in Table 2. Under compressive load, the simple 
DA/Ca(OH).sub.2 cements (Formulations H and I) did not fracture but 
underwent plastic deformation resulting in a marked change in dimensions. 
Only a slight recovery in dimensions was noted after storage in distilled 
water at 37.degree. C. for one month. Cements formulated with additional 
fillers such as tribasic calcium phosphate (HA), TiO.sub.2, SiO.sub.2, 
etc., had improved strength and showed only slight deformation under 
compressive stress. In tension all formulations broke cleanly into halves. 
On prolonged storage in distilled water at 37.degree. C. (7d, 14d) 
DA/Ca(OH).sub.2 cements with HA as filler shows some increase in CS 
(Formulations J, K and L). All these cements have maintained their 
integrity after one year in H.sub.2 O at 37.degree. C. 
The properties of some DA cements prepared with MgO as the base component 
are summarized in Table 3. The salient feature of the DA/MgO cements 
compared to the DA/ZnO and DA/Ca(OH).sub.2 types is the relatively high CS 
(34-58 MPa) achieved at relatively low powder/liquid ratios. Presumably, 
the magnesium dimerate matrix is stiffer and less yielding than that of 
calcium or zinc dimerate as these cements tend to fracture in compression 
as well as tension. As shown by formulation W, the cements maintain their 
integrity and strength on prolonged (7d) storage in water at 37.degree. C. 
Table 4 illustrates a hybrid type of DA cement which uses a binary base 
system of Ca(OH).sub.2 and MgO. Although the CS values are generally 
somewhat lower than those of DA/MgO, these cements have some of the 
energy-absorbing characteristics of the DA/Ca(OH).sub.2 cements in that 
they resist brittle fracture in compression but with only modest 
dimensional changes. In tension clean fractures are obtained. Again, 
prolonged storage in distilled water (7d at 37.degree. C.) did not 
decrease CS. The addition of fillers further enhances dimensional 
stability and strength. 
Table 5 summarizes some physical properties of representative cements 
derived from TA. As noted for the simple DA/Ca(OH).sub.2 cements, the 
analogous TA/Ca(OH).sub.2 cements, also undergo significant plastic 
deformation under compressive stress. The addition of fillers increases 
both the strength properties and dimensional stability. Similarly, the 
TA/MgO based cements have higher CS and also undergo fracture under 
compression. Cements derived from TA and the binary base system of 
Ca(OH).sub.2 -MgO had both energy-absorbing properties, good dimensional 
stability and adequate CS and DTS values (Formulations IV and V). 
SOLUBILITY 
The water solubility of DA and TA cements appears to be generally low, 
varying with the relative solubilities of the base and/or filler 
components. Some representative solubility values are 1.5% for the 
DA/Ca(OH).sub.2 (Formulation I, Table 2); 0.9% for the DA/Ca(OH).sub.2 
with 33% of HA (Formulation L, Table 2); and 0.1% for DA/ZnO, P/L=7 
(Formulation A, Table 1). The last cement, when exposed to a lactic acid 
solution (pH=4) for 24 hours, exhibited only a 0.2% weight loss. 
OPTICAL PROPERTIES 
By proper selection of the base/filler component DA and TA cements with 
various degrees of translucency can be prepared. Some of these cements 
harmonize well with the appearance of enamel suggesting their potential 
for use as esthetic intermediate restorative materials. For example, 
translucent cements resulted from using calcium base powders (e.g. 
Ca(OH).sub.2) with fillers such as fused alumina, pyrogenic silica, and 
various other vitreous fillers. With magnesium base powders (e.g. MgO) 
less translucent cements are formed and zinc base powders (e.g. ZnO) yield 
opaque cements. By proper selection of filler components having refractive 
indices that match the cement matrix and also contain radiopaque elements 
(e.g. Ba, Sr) it is possible to formulate translucent, radiopaque cements. 
The resinous nature of certain metallic salts of both monocarboxylic-(e.g. 
abietic) and dicarboxylic acids (e.g. dimer, azealic) has been recognized 
for some time. The polymeric nature of several divalent dimerates (e.g. 
zinc dimerate) prepared either at high temperatures (fusion method) or at 
ambient temperatures by precipitation from solution (metathesis) is also 
known. Researchers have prepared and characterized a well-defined series 
of divalent metal dicarboxylates (e.g. calcium sebacate) by both methods 
and designated these unique materials, halatopolymers, to denote their 
dual salt-like and polymeric character. 
In contradistinction to the more common ionomer polymers which have 
pendant, crosslinked carboxylate groups, halatopolymers have carboxylate 
linkages in their backbone as depicted below: 
##STR1## 
Thus the setting mechanism involves a series of chain extending, acid-base 
reactions of the polyacid with polyvalent cations. 
According to the present invention it is feasible to prepare dental cements 
having halatopolymeric matrices by the direct reaction of dimer acid with 
a variety of divalent metal base powders. The rate of setting for such 
halatopolymeric cements is determined by the state of subdivision, the 
surface character and the quantity of base powder. The moisture content of 
the components, the presence of accelerators or retarders and the 
temperature of mixing also affect the setting behavior. 
Cements prepared from DA and TA with Ca(OH).sub.2 or CaO only exhibit a 
non-brittle but deformable nature. Compared to commercially available 
Ca(OH).sub.2 liners and pulp capping materials, these cements are stronger 
and more hydrolytically resistant. They also are alkaline in water and 
should provide a protective barrier against acids and other chemicals, be 
antibacterial, and stimulate the formation of secondary dentin. The 
deformable nature of these cements can be largely eliminated by the use of 
MgO as a secondary base and/or the addition of appropriate fillers (e.g. 
Ca.sub.5 (PO.sub.4).sub.3 OH, TiO.sub.2, etc.). In addition to providing 
improved dimensional stability, these reinforcing agents can yield DA and 
TA cements of enhanced strength and hydrolytic durability. 
DA and TA cements prepared with MgO as the sole base have a stronger but 
more brittle, much less deformable nature than those formulated with CaO 
or Ca(OH).sub.2. The use of a binary base system of Ca(OH).sub.2 and MgO 
results in tough, fracture-resistant cements that still provide an 
alkaline environment in the oral cavity. Formulations with ZnO provide 
tough, hydrophobic cements having less alkalinity. 
Because of their bulky nature and relatively low carboxylic acid content 
(16%) these cements are expected to have excellent biocompatibility and to 
show very low contraction on setting. (Preliminary studies using a mercury 
dilatometric method indicate that the hardening of some of these cements 
is accompanied by a slight expansion; a future publication will detail 
these findings.) DA and TA are not corrosive and are classified as 
non-toxic by ingestion and are not considered to be primary skin or eye 
irritants. 
DA and TA cements do not inhibit the free radical polymerization of 
resin-based dental materials and this property permits the formulation of 
hybridresin-composite cements. The versatile nature of these non-aqueous 
types of polycarboxylate cements suggests a number of dental applications: 
cavity liners, pulp capping materials, endodontic filling materials, 
periodontal dressing materials, impression materials, and esthetic, 
radiopaque temporary and intermediate restorative materials. 
Expansion was not a major difficulty in the Ca(OH).sub.2 containing 
cements. These cements preferably have a P/L ratio of about 1-4, and more 
preferably about 2-3. 
It should be noted that compositions J, K and P actually expanded upon 
setting. Likewise, Zn-Al.sub.2 O.sub.3 containing composites also expanded 
upon setting. 
Ca(OH).sub.2 has been found to activate weaker bases, such as MgO. Thus, 
when Ca(OH).sub.2 is employed as part of a binary base, no activator need 
be present. 
As little as 10% MgO has been found to improve the deformation properties 
of Ca(OH).sub.2. MgO/DA and TA cements have been found to undergo brittle 
fracture. Mixtures of MgO and Ca(OH).sub.2 which impart desirable 
compressive strength and fracture resistance preferably include about 
10-70% Ca(OH).sub.2 and a remainder of MgO. More preferably, the mixture 
contains about 60-40% Ca(OH).sub.2 and most preferably it contains about 
50% Ca(OH).sub.2. Similar weight percentages of Ca(OH).sub.2 should be 
employed in other calcium containing powder components used in the present 
invention. 
It is to be understood that the present invention is not limited to the 
embodiments disclosed which are illustratively offered and that 
modifications may be made without departing from the invention. 
TABLE A 
______________________________________ 
BASES AND 
ACTIVATORS USED IN DA AND TA CEMENTS 
Formula 
or 
Name Acronym Form Source 
______________________________________ 
Calcium CaO Powder J. T. Baker Chem. Co. 
Oxide Phillipsburg, NJ 
Calcium Ca(OH).sub.2 
Powder (Thin J. T. Baker Chem. Co. 
Hydroxide Layer Chromato- 
Phillipsburg, NJ 
graphic Grade) 
Magnesium 
MgO Powder J. T. Baker Chem. Co. 
Oxide Phillipsburg, NJ 
Zinc Oxide 
ZnO Powder Proco-Sol Chem. Co. 
(Micronized) Philadelphia, PA 
Acetic Acid 
AA Liquid Fisher Scientific 
Fairlawn, NJ 
Propionic 
PA Liquid Fisher Scientific 
Acid Fairlawn, NJ 
______________________________________ 
TABLE B 
______________________________________ 
CEMENT ADDITIVES 
Formula 
or 
Name Acronym Form Source 
______________________________________ 
Tribasic HA Powder Fisher Scientific 
Calcium Co. Fairlawn, 
Phosphate NJ 
Titanium Oxide 
TiO.sub.2 
Powder Fisher Scientific 
Co. Fairlawn, 
NJ 
Calcium CaSiO.sub.3 
Powder Interpace Corp. 
Metasilicate Willsboro, NY 
Zirconia ZrO.sub.2 
Powder Applied 
(Zirconium Ceramics, Inc. 
Dioxide) Atlanta, GA 
Aluminum Al(OH).sub.3 
Powder Matheson, 
Hydroxide Coleman & Bell 
Norwood, OH 
Aluminum Oxide 
Al.sub.2 O.sub.3 
Powder Alcoa Chemicals 
(Hydral 710) 
Bauxite, AR 
poly(methyl 
PMMA Powder Esschem 
methacrylate) Essington, PA 
poly(vinylidene 
PVF.sub.2 
Powder Penwalt Corp. 
fluoride) (Grade 960 ES) 
Philadelphia, PA 
Ethylene/Acrylic 
PEAA 15% Acrylic Scientific 
Acid Copolymer Acid Polymer Prod. 
Ontario, NY 
______________________________________ 
TABLE 1 
__________________________________________________________________________ 
Properties of DA/ZnO Cements 
24 H. Mechanical 
Strength (MPa) 
Powder Component P/L Ratio 
Set. Time Diametral 
Cement 
In Powder In Liquid 
w/w Min Compressive 
Tensile 
__________________________________________________________________________ 
A ZnO.sup.1 -- 7 7.5 49.4 (2.1).sup.2 
6.5 (0.5).sup.2 
B ZnO.sup.3 -- 7 10.0 46.4 (1.0) 
5.8 (2.5) 
C ZnO.sup.1 (86%), MgO.sup.4 
-- 4 7.0 46.6 (1.0) 
5.7 (0.8) 
D.sup.6 
ZnO.sup.1 ZrO.sub.2 (67%) 
9 9.5 46.6 (4.8) 
6.2 (0.9) 
E.sup.6 
ZnO.sup.5 CaSiO.sub.3 (67%) 
5 3.5 22.0 (1.0) 
8.2 (0.8) 
F.sup.6 
ZnO.sup.1 PEAA(5%) 
7 9.0 45.6 (1.3) 
5.7 (0.4) 
G.sup.6 
ZnO.sup.1 PEAA(10%) 
7 9.5 46.9 (2.2) 
5.6 (0.6) 
__________________________________________________________________________ 
.sup.1 Micronized ZnO 
.sup.2 Standard Deviation 
.sup.3 Activated with 0.5% PA 
.sup.4 Activated with 1.0% AA 
.sup.5 Activated with 2.0% PA 
.sup.6 Resisted fracture under compression at crosshead speed of 1 mm/min 
TABLE 2 
__________________________________________________________________________ 
Properties of DA/Ca(OH).sub.2 Cements 
24 H. Mechanical 
Strength (MPa) 
Powder Component P/L Ratio 
Set. Time Diametral 
Cement 
In Powder 
In Liquid 
w/w Min Compressive 
Tensile 
__________________________________________________________________________ 
H -- -- 1 7.5 26.7 (0.2).sup.1 
-- 
I -- -- 1.5 3.0 24.6 (0.5) 
4.2 (0.7) 
J -- HA (50%) 
2 6.0 31.6 (1.0) 
5.2 (0.4) 
33.8 (1.2).sup.2 
K -- HA (33%) 
2 7.0 30.8 (1.9) 
-- 
L HA (33%) 
-- 2 7.0 32.0 (0.6) 
5.7.(0.6) 
37.0 (0.5).sup.3 
M TiO.sub.2 (50%) 
-- 3 7.0 29.7 (1.1) 
5.8 (0.8) 
N Al(OH).sub.3 (50%) 
-- 33 8.0 26.6 (0.2) 
4.9 (1.0) 
O -- Al(OH).sub.3 (67%) 
3 9.0 28.6 (1.8) 
5.2 (0.3) 
P SiO.sub.2.sup.4 (75%) 
-- 4 3.0 26.9 (0.9) 
6.7 (0.5) 
Q PMMA (56%) 
-- 3 5.0 23.3 (0.5) 
-- 
__________________________________________________________________________ 
.sup.1 Standard deviation 
.sup.2 7 day storage in distilled water at 37.degree. C. 
.sup.3 14 days storage in distilled water at 37.degree. C. 
.sup.4 Silanized with 2% 2carboethoxypropylmethyldiethoxysilane and heate 
4 hrs at 250.degree. C. 
TABLE 3 
__________________________________________________________________________ 
Properties of DA/MgO Cements 
24 H. Mechanical 
Strength (MPa) 
Powder Component P/L Ratio 
Set. Time Diametral 
Cement 
In Powder 
In Liquid 
w/w Min Compressive 
Tensile 
__________________________________________________________________________ 
R MgO.sup.1 
-- 1 6.0 35.2 (1.0) 
3.8 (0.2) 
S MgO.sup.2 
-- 2 35.0 50.2 (2.3) 
4.9 (0.4) 
T MgO.sup.3 
H (50%) 2 9.0 58.2 (2.2) 
5.3 (0.7) 
U MgO.sup.3 
Al.sub.2 O.sub.3 (50%) 
2 6.0 50.7 (0.8) 
4.9 (0.7) 
V MgO.sup.3 
ZrO.sub.2 (75%) 
4 6.5 55.1 (3.0) 
5.0 (0.7) 
W MgO.sup.3 
TiO.sub.2 (67%) 
3 6.0 55.8 (1.5) 
5.0 (0.6) 
56.6 (3.3) 
X MgO.sup.3 
CaSiO.sub.3 (67%) 
3 7.0 45.2 (1.8) 
7.2 (1.0) 
Y MgO.sup.3 
PMMA (60%) 
2.5 9.5 43.0 (0.3) 
3.8 (0.5) 
Z MgO.sup.3 
PVF.sub.2 (67%) 
3 9.0 33.9 (2.3) 
3.6 (0.3) 
__________________________________________________________________________ 
.sup.1 Activated with 1% AA 
.sup.2 Coated with 1% ascorbyl palmitate from CH.sub.2 
.sup.3 Activated with 1.5% PA 
.sup.4 7 day storage in distilled water at 37.degree. C. 
TABLE 4 
__________________________________________________________________________ 
Properties of DA/MgO--Ca(OH).sub.2 Cements 
24 H. Mechanical 
Strength (MPa) 
Powder Component P/L Ratio 
Set. Time Diametral 
Cement 
In Powder 
In Liquid 
w/w Min Compressive 
Tensile 
__________________________________________________________________________ 
a MgO (50%) & 
-- 1 4.5 30.4 (2.2) 
3.3 (0.3) 
Ca(OH).sub.2 (50%) 
b MgO (50%)& 
-- 1.5 4.0 34.6 (1.6) 
-- 
Ca(OH).sub.2 (50%) 
c MgO (60%) & 
-- 3 5.5 43.8 (0.8) 
5.5 (0.5) 
Ca(OH).sub.2 (40%) 
d MgO (50%) & 
HA (50%) 
2 6.5 40.5 (2.0) 
6.0 (0.9) 
Ca(OH).sub.2 (50%) 
e MgO (50%) & 
TiO.sub.2 (50%) 
3 6.5 47.5 (1.2) 
5.6 (1.0) 
Ca(OH).sub.2 (50%) 
f MgO (50%) & 
CaSiO.sub.3 (67%) 
3 2.5 34.5 (1.2) 
6.0 (0.5) 
Ca(OH).sub.2 (50%) 
g MgO (50%) & 
Fuji II 3 9.0 32.4 (0.6) 
6.3 (0.7) 
Ca(OH).sub.2 (50%) 
Powder (67%) 34.7 (0.5).sup.1 
h MgO (23%), 
-- 5 5.0 30.4 (0.6) 
3.8 (0.5) 
Ca(OH).sub.2 (23%) & 
PMMA (54%) 
__________________________________________________________________________ 
.sup.1 7 days storage in distilled water at 37.degree. C. 
TABLE 5 
__________________________________________________________________________ 
Properties of Trimer Acid (TA) Cements 
24 H. Mechanical 
Strength (MPa) 
Powder Component P/L Ratio 
Set. Time Diametral 
Cement 
In Powder 
In Liquid 
w/w Min Compressive 
Tensile 
__________________________________________________________________________ 
I Ca(OH).sub.2 
-- 1.5 4.0 22.6 (0.5) 
3.7 (0.2) 
II MgO.sup.1 
-- 2.0 6.0 27.7 (0.7) 
2.8 (0.3) 
III MgO.sup.2 
TiO.sub.2 (67%) 
3 6.0 60.4 (1.4) 
-- 
IV MgO (50%) & 
TiO.sub.2 (67%) 
3 10.0 42.9 (0.6) 
6.6 (0.5) 
Ca(OH).sub.2 (50%) 
V MgO (50%) & 
HA (50%) 
2 9.0 46.7 (1.7) 
6.1 (0.6) 
Ca(OH).sub.2 (50%) 
__________________________________________________________________________ 
.sup.1 Activated with 1% AA 
.sup.2 Activated with 1.5% PA