US2617193A - Method of impression-taking in relining dentures - Google Patents

Description

Nov. 11, 1952 B, D. RANDALL 2,617,193

METHOD OF IMPRESSION-TAKING IN RELINING DENTURES Filed April 28, 1950 2 SHEETS-SHEET 2 Inventor; fierzno fi. fiarzdzZZ, y 7% 27 Patented Nov. 11, 1952 UNITED STATES PATENT or fice];

METHOD OF IMPRESSION-TAKING IN RELINING DENTURES Benno D. Randall, Boston, Mass.

Application April 28, 1950, Serial No. 158,888

1 Claim. 1

This invention relates to a method of relining artificial dentures, and pertains more particularly to an improved method or technique; of impression-taking in the process of relining or rebasing full lower dentures.

As is well understood .by the dental profession, the relining of full, lower, artificial dentures is necessary in most instances, at variable periods of time following the original insertion of the denture, because of progressive atrophic changes which take place in the mandible on which the denture rests. Due to such atrophy, stability of the denture is lost, discomfort to the wearer increases, and speech and mastication are-impaired. In order to overcome these conditions, it is necessary to reline the denture to conform to the new anatomy of the mandible, or to construct a new denture.

Heretofore, the conventional method of impression-taking for relining a full lower denture has involved placing an impression medium in the groove of the denture which rests on the gum tissues over the mandible, without changing the form of the denture or otherwise preparing it for the reception of the impression material; inserting the denture (filled with the impression material) into the patients mouth, in its normal position; having the patient close the mouth and hold the denture in position bypressure from the upper teeth, so that the impression material conforms to the shape of the mandible; and removing the denture after the material has hardened. This technique is known to the profession as the pressure method of impression-taking.

The use of the pressure method has several unsatisfactory results. For example, pressure on the filled denture forces the soft and removable gum tissues away from their normal rest positions over the mandible, and the tissues will thus be forced to abnormal positions when the relining is used; and such unnatural pressure, applied to a mandible uncushioned by gum tissues, causes more rapid bone atrophy and thus requires more frequent relining of the denture and causes eventual attrition of the alveolar ridge of the mandible, until the patient is no longer able to use a lower denture efficiently or comfortably. Moreover, the relined denture is unduly thickened, resulting in the destruction of the correct facial and bite distances which were carefully restored by the original denture, and immediately afiecting the physical and mental comfort of the wearer.

It is, therefore, the principal'purpose of the present invention to eliminate the unfavorable results of the conventional pressure method of 2 i impression-taking for the purpose of .relining lower dentures, by providing an improved technique which obviates-the tissue-distorting pressures discussed above, and also avoids unnecessary or excessive thickening of the denture. The improved method, which may be termed a none pressure impression technique, obtains a true impression of the soft and movable gum tissues,'in' their normal or rest positions, over the mandible, and retains the restored facial and bite distances of the original denture.

More specifically, it is an object of this invention to achieve these desirable results by so preparing the lower dentures, before the application of the impression material thereto, that the denture will hold an adequate quantity of the material in a plastic state, and will permit the plastic material to flow under very gentle pressure and conform to the gum tissues without distorting or displacing them from their normalv positions.

This preparation involves the removal of a substantial portion of side ribs or flanges of the denture, and a lesser portion of the bottom of the groove between the flangeawhileleaying contact spots or stops of the original denture. The stops are preferably provided at the respective retromolar triangles or pads, and at-the'bottom of the original denture groove at opposite sides of the cuspid area, so that the prepared denture may be accuratelyrefitted to-the'patientsmouth during the taking of th impression.

After the artificial denture has been prepared and the impression has been taken in accordance with this invention, a model of the hardened impression material is poured and invested, and the liner of denture materialis prepared and bonded to the denture case in accordance with common practice.

The novel technique in the preparation of a lower denture, in accordance with this invention, is illustrated in the accompanying drawings, in which:

Fig. 1 is a plan view of the grooved or gum tissue side of the lower denture which is to be relined;

Fig. 2 is a section on line 22 of Fig. 1;

Fig. 3 is a view similar to Fig. 1, after portions of the denture have been removed to leave the contacts or stops herein described, in preparing the denture for impression taking;

Fig. 4 is a section on line 4-4 of Fig. 3;

Fig. 5 is a diagrammatic side view, partly broken away and in section, showing the prepared denture fitted to the lower jaw, with impression material between the denture and the gum;

Fig. 6 is a section on line 6-6 of Fig. 5;

Fig. 7 is a side view of a plastic model made from the original denture, before preparation or treatment, with the denture applied thereto; and

Fig. 8 is a view similar to Fig. 7, showing the prepared denture applied to the model.

As illustrated in the drawings, the improved denture rebasing method is devised to provide a relining for afull lower denture II which has previously been preparedand fittedto a patients mouth, and worn for a period of time. The

denture has an arcuate groove 12 which receives the tissue-covered alveolar ridge of the mandible,

and peripheral margins or flanges l3i 'which' ex-e' tend along the lingual and buccal areas," on op posite sides of the groove I2, to embrace the ridge. The retromolar triangles or pads are indicated at M.

In accordance with this invention, before tak: ing the new impression for the purpose of making a liner for the case II, the flanges I3 and a portion of the bottom of the groove-I Z'are ground away to remove most of fthesurface which normally contacts the-soft, movable gum tissues,- while leaving; intact the retromolar padsl4- and two contactpoints orstops I5 -at-the opposite sides of the cuspidarea intact. The removed portions are 'indicated by broken lines'in Fig: 4, the denture material atth'e bottomof thegroove l2 'being removed-to a depth of not more than 2mm. Thus, the opposite flanges l3 are totally removed and only four points or spots of the original gum-contacting surfaces of "the denture are left intact, namely, the retromolar pads 14 and the cuspid stops l5."

Before the denture is thus prepared, dental plaster or artificial stone is poured into the groove I2 or gum tissue sideof the original denture, toproduce amale model,- representing thepatients lower gums, as indicated at l9 in Figs. 7 and 8. The denture is "removed from the hardened model "and thefour-stop-areas l4; l4 and l5, 15 are suitablymarked in outline on the gum tissue side-of the denture. Theremaining surfaces of the-gum tissue side of the denture, and the-entire fiangedperipherythereof, are reduced or removed b'y-grinding,- (mother-- wise, ,as aforesaid, to thenew surface l1.

During the grinding operation-, the denture H maybe replaced on=-the-model I9-'from time to time, with thefour stops contactingtheridge of the model, to determinewhether the reduced areas have-beensufliciently removed so that the remaining surf aces are out of contact with the model (Fig. 8).- The'spacing-shouldbe approximately two millimeters. Thus the denture may be accurately reduced in preparation for impressiontaking; at the dental laboratory 1 without repeated fittings to the patients mouth. A final fitting to the mouth is desired however, before the impression material is applied to the prepared denture; and any imperfections are corrected by the dentist.

Suitable impression material (6 is then poured onto the prepared surface of the denture, and the dentureis placed in the patients mouth to take the non-pressure impression. The denture is floated down with light pressure to its proper position over the mandible 18, as determined by the four location stops which lightly contactthesofttissues. The patient then gently closes the mouth and maintains light pressure on the denture until the material sets. The light pressure is exerted on the gum only at the four contact areas; :there is little or no pressure on the plastic impression material l6 which freely flows-between the reduced surface I! and the gum tissues, without displacing the movable tissuesfrom their-normal rest positions.

When. the impression-material has set, the denture isremoved from the patients mouth, another'model is poured and invested, and the denture is relined or rebasedin accordance with accepted laboratory procedure.

The preparationot'the denture prior to impression-taking provides arebased denture which will fit accurately and comfortably in the patients mouth, without distorting the soft gum tissues, and whichwilleliminate rapid atrophic changes in' the'mandibleand hence obviate frequent relining of the denture.

I claim:

A method"ofimpression-taking' for relining lower dentures which consists in removing substanti'al portions of the'gum-contacting surfaces of the denture, while leaving intact a plurality of relativelysmall', spaced, gum-contacting supports at 1 the respective retromolar and cuspid areas, applying plastic impression material to the denture, and: taking anon-pressure impression in the mouth of the patient while the impression material is plastic'and free-flowing.

BENNO D. RANDALL;

REFERENCESLCITED The'following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,887,749 Bowers Nov. 15, 1932 2,036,715 Morgan Apr. '7, 1936 2,165,597" Widoe, Sr. July 11, 1939 2,466,727" Morgan Apr. 12, 1949

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