A new vibrator for amalgam condensation and removal of calculus

A new vibrator for amalgam condensation and removal of calculus

A NEW VIBRATOR FOR REMOVAL OF CALCULUS AMALGAM CONDENSATION AND SAM KARLSTR~M, ODONT. DR. G&de, Sweden IN THE CONDENSATION OF AMALGAM is to pack t...

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A NEW VIBRATOR FOR REMOVAL OF CALCULUS

AMALGAM

CONDENSATION

AND

SAM KARLSTR~M, ODONT. DR. G&de, Sweden IN THE CONDENSATION OF AMALGAM is to pack the amalgam crystals together so that the minimum amount of mercury is required for cohesion. The amalgam must retain its plastic properties so that it can be worked easily. Similar conditions apply in the modern concrete industry. The solid particles are compactly arranged so as to obtain a product with the greatest possible density, compactness, strength, and hardness with the minimum dimensional changes.

T closely HE

AIM

VIBRATION

METHOD

The “stamping method” was used in the concrete industry until 1917. By this method, the strength and homogeneity of the material are increased by subjecting it to a series of blows (stamping). The same year, the French engineer E. Freyssinet introduced a completely new method of making concrete-the “vibration method.” This method constituted a revolution in that field and is now used to the exclusion of all others. Freyssinet’s method involves the use of mechanical equipment to produce rapid vibration in the recently stirred concrete. Through the kinetic energy thus supplied, the solid particles in the mass are subjected to forces that reduce the static friction between them and set them in motion. The particles execute soft, elastic oscillations and are regrouped so that there is the minimum of space between them. The characteristic of these forces is that they are not applied as blows but as soft, elastic, sine curve oscillations. In fact, the force may be regarded as a tone that penetrates the concrete at a certain velocity. The principles applied in the amalgam technique are those followed in the concrete industry before the time of Freyssinet. The condensation is effected by applying the greatest possible mechanical pressure ; to increase the effect, use is made of automatic mallets which rely chiefly on impulse action. Clearly, this treatment of subjecting amalgam to impulses cannot be called a true vibration. Therefore, the same effect cannot be achieved. INKA

INTRAORAL

VIBRATOR

The Inka intraoral vibrator is an amalgam condenser that is designed according to the principles used by Freyssinet. This instrument is a further development of the vibrators described previous1y.l 586

“N:‘EE: ‘3”

VIBRATOR

FOR

AMALGAM

CONDENSATION

AND

CALCULUS

587

The moving components of the instrument (Fig. 1) are enclosed in a cylindric steel casing (1) . One end of the casing is open and designed for connection directly to the dental engine. The other end, the vibrator head (Z), is closed so that the interchangeable points can be fixed therein. The vibrations are produced by a rotor (3) which consists of a cylindric oscillating rod that rotates about its own axis as a centrifugal pendulum. The free end of the rotor is shaped as a hollow body (4) and rolls on a pin (5). The pin constitutes the inner part of the vibrator head, which is firmly attached in the cylindric casing. The cylindric rod (3) is connected to the driving shaft of the dental engine (6‘) by means of an elastic coupling (7). The coupling is arranged to allow free

Fig.

I.-A

sohematic

diagram

of the

Inka

intraoral

vibrator

showing

the

internal

components.

oscillation of the rotor in relation to the driving shaft. The rod cannot rotate independently of the shaft. The coupling consists of a rubber sleeve inserted between the end of the driving shaft and the rotor, which overlap one another. The vibrator head is provided with two channels (8, 9)) drilled at different angles, which take the points. One channel makes an angle of 25 degrees with the axis of the vibrator, and the other is perpendicular to the former. Since one of the channels passes through the head, it is possible to insert the points from either end. Thus, there are three positions for the point, one of which makes an angle of 65 degrees backward with the axis of the vibrator. The points are shaped differently according to the purpose for which they are intended, for instance, a spatula, a chisel, a knife, a disc, a tenon, and a spherical body (Fig. 2). The shaft of .the point, the diameter of which is slightly less than that of the channel, is flexible and slightly curved. When the shaft is pushed into the channel, it is held firmly by friction in any desired position. The rotor and the driving shaft, which are connected to the dental engine by a cIaw coupling (Fig. 1, ZO), have their bearing in the cylindric casing by means of a piston (11) . A fixed pin (12) in the piston passes out through a longitudinal slit (13) in the casing. The pin permits the rotor with the piston and the driving shaft to be withdrawn from the casing for inspection or change of the rotor. For practical reasons, the number of rotors at present is limited to two-a light one used for vibration of amalgam and the other, a heavier one, intended chiefly

KARLSTRGM

588

J. Pros. Den. May-June, 1960

for removal of dental calculus. The higher amplitude of the heavier rotor gives a greater penetrating effect. Therefore, with the aid of a chisel or knife-shaped, slightly convex point, calculus can be more effectively scaled from the surfaces of teeth. CLEANING

THE

VIBRATOR

If the surfaces of the hollow body (Fig. 1, 4) and the pin (5) become contaminated with oil, slipping will occur and the efficiency of the instrument will be reduced. The surfaces must be kept clean with a grease solvent such as chloroform, ether, or trichloroethylene (benzine is unsuitable).

Fig. 2.-The Inka intraoral vibrator has various types of points and two rotors. The light rotor is used for the condensation of amalgam. The heavier rotor, with greater amplitude and penetrance, is intended chiefly for the removal of dental calculus.

For the vibrator to work at the maximum efficiency, it should be cleaned regularly at short intervals, especially when it is new. This is particularly true if the apparatus becomes warm during use. A specially designed instrument known as the cleaning rod is used to facilitate the cleaning operation. This rod has the form of a solid aluminum cylinder but is somewhat longer than the vibrator casing (l), into which the rod can be inserted by virtue of its smaller diameter. One end of the cylinder is drilled out to a depth of about 1 cm. and threaded. The diameter is sufficiently large for the end of the rod to pass loosely over the pin (5) when the rod is inserted into the vibrator casing. To clean the vibrator, a plug of cotton wool dipped in the cleansing fluid is inserted into the casing. Then, the rod is inserted into the casing so that it presses

Volume Number

10 3

VIBRATOR

FOR

AMALGAM

COKDENSATIOX

.4ND

589

CALCC’LYS

the cotton wool around the pin (5). The pin is cleaned by turning the rod clock7&e. The cotton wool catches in the threads and accompanies the rod as it is removed when the cleaning operation is complete. The process may be repeated several times as required. The other end of the aluminum rod is shaped as a threaded pin, which is used for cleaning the hollow body (4) that rolls on the pin (5). The same procedure as described is followed. The vibrator described is designed for connection to a slip joint. In order that the vibrator may be used also with the Doriot straight handpiece, some modifications of the design have been made. The resulting instrument is only about one-half as long as the one for the slip joint. This shorter instrument is connected

Fig.

3.-Two

Doriot

straight

handpieces, the standard

one with contra-angle

the

intraoral handpiece.

vibrator

and

the

other

with

to the Doriot straight handpiece in the same way as the contra-angle handpiece. The total length of the Doriot handpiece with vibrator will then be slightly less than the total length of the Doriot straight handpiece with contra-angle handpiece (Fig. 3). A pair of tweezers and a plug of cotton wool dipped in the cleansing fluid are used to clean this instrument. ADVANTAGES

OF

THE

INKA

VIBRATOR

The Inka intraoral vibrator

has many advantages.

( 1) It provides soft, elastic, sine curve vibrations. The tone that is sent through the amalgam has a penetrating effect so that the entire mass is affected. The efficiency is increased also, because the instrument gives a frequency several

590

KARLSTRGM

J. Pros. May-June,

Den. 1960

times greater than is obtainable with other amalgam condensers. Experiments have shown that the soft vibration provided by the Inka intraoral instrument is better tolerated, especially by children, than the percussion effect. (2) Pressure is not necessary for the amalgam mass to be affected by the instrument. It suffices for the vibrator point to come into contact with the amalgam for it to melt, just as when a warm instrument is brought into contact with a wax surface. Therefore, there is no risk of the amalgam of a contour filling being expelled from the cavity by a pressure applied during condensation. (3) The points used for the condensation of the amalgam may be placed in the vibrator in three directions. The instrument may, therefore, be used easily in any situation that may arise in the mouth. The number of points required also is kept to a minimum. (4) The point is rotatable about its axis and remains firmly in position even under the vibrational stress. The point can be rotated in various positions while the vibration is in progress. This increasesthe range of application of the instrument. (5) Since the point is fixed firmly in position, the instrument can be used as an ordinary amalgam plugger or as a combined plugger and vibrator. The vibrator is not damped when pressure is exerted with it. (6) Changing of the points requires only a moment and is considerably quicker than changing burs in the handpiece. Thus, the condensation procedure can be performed rapidly before the amalgam has hardened. (7) When the larger rotor is fitted, the Inka intraoral vibrator can be used for removing dental calculus. (8) The vibrator casing is easily sterilized by the usual procedures. REFERENCE

1. Karlstrijm, Sam: The PontostructorMethod for the Constructionof Fixed Bridges,Crowns and Inlays, Stockholm,1955,NordiskaBokhandeln,p. 73. NYCATAN GXVLE,

37 SWEDEN