sterilizing them. Saturating them with alcohol and burning it off is recommended; with a touch of oil to threads, after each sterilization, this should prevent them from binding.

Not only do the Perry separators establish and maintain separation during the operation but they relieve strain on the peridental fibers to a large extent by lifting the teeth slightly from the alveolus when properly adjusted. They also will tighten up on loose contacts between adjacent teeth, thus a filling may be inserted which will restore the contact of the tooth in which it is placed and maintain contacts between the adjacent teeth. Contacts are so often reduced in mature adult life through abrasion of tooth surfaces during normal mastication due to individual tooth movement; also this may occur as the result of traumatic occlusion, and, last but not least, bodily movement of adjacent teeth or drifting, as it is termed, may have resulted from the existence of the vary carious area which is being cut away and filled.

The details set forth above go for naught unless a properly balanced alloy is used. Shrinkage is absolutely contraindicated, and to avoid this alloys should be used which show an initial expansion of not more than three ten-thousandths of an inch. This slight expansion is considered advantageous, as it locks the filling in the cavity so tightly that space for bacteria to enter does not exist around the margins. The use of such an alloy when properly inserted also prevents discoloration of tooth structure, as in the past the most prolific cause of this annoying factor has been found to be an improper adaptation of the filling material to the cavity walls and margins either through a poor operative technic or the use of a low-grade alloy. The Navy supplies a balanced Black alloy, so that one factor in a careful technic is cared for.

Dr. Thomas P. Hinman some years ago conducted a series of tests of the manipulation of amalgam by sending to prominent dentists in different parts of the country prepared cavities and asking them to fill these with amalgam according to their usual procedure and to return them to him for tests. He failed to find a filling which was so accurately adapted to the cavity walls that it would withstand a few pounds of air pressure without leaking. The conclusions reached were that all who had inserted fillings for the tests used the amalgam too dry, or, in other words, that from which too much mercury had been expressed before the material was packed in the cavity. To overcome the defect he advocated a technic resembling that given in this paper.

Insert the filling, taking advantage of its plasticity and adaptabil ity, and then remove the excess mercury. A filling placed according to the details set forth will be a revelation to those who have not practiced this method or seen it demonstrated.

THE RELATION OF MODERN DENTISTRY TO GROUP DIAGNOSIS AS CONDUCTED AT THE NAVAL HOSPITAL, SAN DIEGO, CALIF.

By L. C. Montgomery, Lieutenant, Dental Corps, United States Navy.

The dental surgeon who aims to practice successfully preventive dentistry should not only be well grounded in his own special branch but should have a good working knowledge of general medicine, in order that his attention may be directed to hidden foci of infection connected with the teeth which may be responsible for an obscure pathological condition in some distant part of the body.

The danger which may lurk in a hidden dental infection is not fanciful. Dr. Lewellys F. Barker, of Johns Hopkins Hospital, speaking in this connection in reference to Streptococcus viridans, said: "I have personally observed 20 cases of viridans endocarditis, and every one of the patients is dead." So we may see the dental surgeon has a grave responsibility in treating infections of the teeth.

In a paper read before the Chicago Dental Society in 1913, Dr. Charles H. Mayo remarked: "The next great step in preventive medicine must come from the dentists. Will they make it?" Following this hint there came a deluge of extracted teeth-good, bad, and indifferent-removed without serious study and before the development of the diagnostic methods available to-day. Naturally there occurred a reaction, in which there was a tendency to refrain from dental interference until systemic conditions justified the removal of the teeth. The tendency to-day is to endeavor to make an early diagnosis, and if the pathological condition of a tooth points to an unfavorable prognosis prompt removal is indicated.

A great deal can be done, however, to preserve a tooth by proper treatment. By cleaning out and filling all cavities and smoothing the margins of restorations much infection may be removed and even cancer of the tongue prevented. Teeth properly treated may remain in a sound condition for years. This fact was recently pointed out by Dr. U. G. Rickert, of Ann Arbor, Mich., who, in an address before the New Jersey State Dental Society in May, 1922, said: "We have convincing evidence that properly treated teeth may remain aseptic for many years, having cultured cases that were found aseptic at the apices many years after treatment."

Treated teeth should be frequently examined by the X ray and subjected to a pulp test by heat or preferably electricity. Teeth which are clinically sound and show no defect when examined by roentgenography may be found to be nonvital by the pulp test. Transillumination of the teeth and adjacent structures will frequently throw light on pathological conditions. Treated teeth-that

is, those which have been subjected to conservative pulp surgery under aseptic conditions-in which the apices are not denuded and which contain a well-inserted root canal filling passing into but not through the apex and which resemble adjacent healthy teeth in that there is no destruction of the surrounding tissue should be considered healthy. However, as root canal filling is a preventive and not a curative procedure, these teeth require frequent inspection.

Grieves places those dental diseases which may become a starting point of general infection into two broad groups, (a) gingival and (b) pulpal and apical. In connection with the gingival he remarks: "All teeth hopelessly undermined by loss of attachments should be removed," and, in speaking of the other group, he says: "Because of certain histo-pathological facts diseased apices, said to be comparable to infected bone sequestræ, can not be exfoliated like these infected bone areas, but are retained by healthy middle and gingival third attachments. Hence apical abscesses involving subapical bone are not cured, like osteomyelitis, by free drainage and removal of a sequestra. Once this labyrinth is engorged with cocci its sterilization is impossible except by such powerful germicides as produce apical necrosis and involve the attaching tissue in apical disease."

Doctor Barker informs us that: "The method of procedure at Johns Hopkins Hospital is to study the mouth in all cases of arteriosclerosis and of arterial hypertension in order to detect there any source of infection that may signify danger. They do that not only in the cases here mentioned but in every patient who comes for diagnostic study. A report from an expert dental diagnostician is considered, with other accumulated data, before the final diagnosis is made." Dr. Frank Billings states: "To investigate and manage these patients [suspected of possessing foci of infection] requires the teamwork of the clinical and laboratory workers. The clinician must carefully examine the patient, exhausting every detail in personal history. The skill of the dentist, the nose and throat specialist, the gynecologist, the genito-urinary expert, and others may be necessary to locate the foci of infection. Each focus must be destroyed." The conclusions of the workers in the Mayo Foundation in this regard are that all teeth showing definite pathology should be sacrificed, and that every patient admitted to the hospital should have a complete oral examination. Thus we see that the dentist has an important place in "group practice."

The following cases illustrate how the dentist may be of great assistance to the physician and the surgeon in connection with the eradication of foci of infection in or about the teeth which are the source of a general infection.

Case 1.-Arthritis: For the past four years the patient had suffered from pain, swelling, and stiffness of elbows, knees, ankles,

and wrist joints. When he came under observation the head of the first phalanx of the right great toe was swollen and painful. Tonsils had been removed. A careful examination by other members of the diagnostic group revealed no focus of infection which could be considered responsible for the condition. The dental examination revealed infection of four impacted molars and areas of pyorrhea about the upper and lower anterior teeth.

Following the extraction of the impacted molars and treatment of the pyorrhea there was a gradual subsidence of the joint symptoms. The patient was discharged from the hospital well six months ago and has had no return of his trouble.

Case 2.-Arthritis: In February, 1919, the patient began to have pain and swelling in the right ankle which troubled him from time to time for two years. On admission to the hospital the ankle presented the symptoms of a severe arthritis. The general physical examination was negative. Dental examination showed roots of teeth Nos. 3, 4, and 14 present and teeth Nos. 13 and 31 nonvital with radiolucent areas. The roots and teeth were extracted and a short chain streptococci obtained on culture. Following the extractions the condition in the ankle subsided, and the patient was finally discharged from the hospital cured.

Case 3.-Suspected chronic pulmonary tuberculosis: The patient on admission to the hospital complained of cough, night sweats, loss of weight and strength. Had never noticed expectoration of blood. A physical and an X-ray examination of the chest revealed no evidences of tuberculosis. Tubercle bacilli were never found in the sputum. The dental examination revealed eight infected teeth, which were removed. Cultures from these teeth showed the infecting organism to be a chromogenic, short chain hemolytic streptococci. Following dental treatment there was rapid improvement. Case 4-Suspected chronic pulmonary tuberculosis: No evidence of tuberculosis or syphilis found on physical and X-ray examination. Two infected roots were removed from under bridges, and four infected teeth were removed. Following the extractions the patient gained 11 pounds in 37 days, cough and night sweats disappeared, and temperature became normal. He was discharged

cured.

Case 5.-Goiter: Examination showed very slight enlargement of thyroid gland, accompanied by slight tremor of extremities. Slight exophthalmia and tachycardia. Pulse rate 116 per minute; after exercise, 136; two minutes later, 116. No subjective symptoms. X-ray report: No evidence of substernal thyroid gland.

Dental report: Both lower first molars nonvital and canals not properly filled. Both lower third molars impacted and show infected areas. Upper right first molar nonvital and granuloma present.

Cultures from first molars and areas around the third molars positive for short-chain streptococci. Wassermann negative, as were other reports from various departments.

The infected teeth were extracted during February, 1922; and at the time of his discharge from the hosptial, March 23, 1922, the following entry was made in his health record by his ward medical officer: "Operative interference not indicated. Since extraction of infected and impacted teeth, with accompanying rest, the thyroid symptoms have shown marked improvement and the patient states his condition does not bother him."

Case 6.-Psychoneurosis: History-broncho-pneumonia 1917; complete recovery; rheumatism January and February, 1919. His present trouble started in 1918, with pain in lower part of back and right side and continued to get worse until he was sent to the hospital.

Present complaint: Back hurts when patient attempts heavy lifting. Is nervous and has palpitation of the heart and a fine tremor of head and upper extremities. Also a tremor, but not so marked, in lower extremities. Experience sharp knifelike stabbing pains in epigastrium.

Examination showed head normal; pupils equal reaction to light and accommodation. Tongue protrudes straight, throat and thyroid negative. Deep muscle reflexes normal. No Romberg. Abdominal and cremasteric reflexes normal. Abdomen negative; Wassermann 4 plus; urine negative; and oral examination discloses an advanced stage of pyorrhea. Cardiac enlargement, aortic and systolic lesions, complains of precordial pain, nervousness, loss of weight and strength. Lungs-fine râles, increased respiration. White blood count 15,000, differential; 68 per cent polymorphonuclear, 1 per cent eosinophiles, 30 per cent lymphocytes, 1 per cent large mononuclear. Treatment: The patient was given eight doses of salvarsan, after which the Wassermann reaction became negative. Following this, all teeth were extracted. The bone tissue was so necrotic that under the most careful manipulation the entire floor of each antrum was carried away during extraction of upper teeth. It was necessary to fill in soft tissue by a plastic operation to keep food from backing into the antrum. When this patient was first examined he was bed fast, weight 96 pounds, and unable to turn over, with apparently a multiple arthritis. Following extraction of all teeth, the arthritis disappeared, the patient gained 29 pounds, and the aortic lesion was imperceptible with only a slight systolic murmur.

Case 7.-Toxic amblyopia: Three months before admission to the hospital the patient noticed rapidly diminishing vision in the left eye. On admission, his Wassermann test was negative, and the left eye presented a complete ciliary paralysis with a low-grade