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Bacteriologic Tests for Root-Canal Sterility
BACTERIOLOGIC TESTS FOR ROOT-CANAL STERILITY B y M orton F . Y a t e s , D .M .D ., and F red W . M o rse , J r ., M .D ., Boston, Mass.
I
N the light of modern scientific re search, root-canal therapy can be at tempted only under conditions of strict asepsis and when the progress of treatment is bacteriologically checked. T h e old method of determining the condition of the canal by the absence of odor or moisture can no longer be deemed adequate, in view of our present knowl edge of biologic processes. M ost practitioners have failed to make use of this scientific control of treatment mainly because of the supposed expense involved. It is generally believed that this procedure requires an elaborate equipment plus medical training to in terpret the findings. This is not the case, for already m any modern dental offices are depending on bacteriologic controls in all root-canal cases and are finding that such a procedure does not require expensive equipment or involve compli cated tests. L e t us first consider the clinical re quirements for carrying out the technic, and later the equipment for incubation and the culture material needed. T h e first and most important require ment is that all operations be carried on under strict asepsis, as otherwise the bac teriologic findings have no meaning what ever. This requires, first, a sterile field of operation; that is, a field painted with tincture o f iodine, with the rubber dam in position. A ll instruments to be used should be freshly sterilized and kept aseptic by being placed in a tray containing 70 per From the Harvard Dental School. Jo u r. A .D .A . & D. Cos., Vol. 25, September 1938
cent alcohol or some other suitable steri lizing solution. A sterile pan should be provided, of white enamel, possibly 4 by 5 by 2 inches, and containing cotton pledgets, J & J paper points, sterile gauze, cotton rolls, short pieces of orthodontic wire 26-gage, about 1 or 2 inches long, to be used as diagnostic wires for meas urement of the canal, and two dental towels. T h e pan should be wrapped in a piece of sheeting and fastened with pins. These pans m ay be prepared in the office, several at a time, and, if it is con venient, can be sent to a near-by hospital for autoclaving. T h e sterilization of the pans can be done in the office by using an ordinary pressure cooker with a pressure gage. Tw e n ty pounds pressure maintained for from fifteen to twenty minutes is suffi cient. T h e pans m ay be baked in a gas or electric range oven at 16 0 ° C . (or 3 2 0 ° F .) for one hour and a half. A ll modern gas and electric ovens are equipped with thermostats, which will maintain any de sired temperature. These pans, if prop erly wrapped after sterilization, m ay be kept in the office for some time without danger of contamination. A S E P T IC T EC H N IC
W ith the rubber dam in position and the field painted with tincture of iodine, the pins holding the covering of the sterile pan are carefully removed. W ith cotton pliers, the tines of which have been flamed by dipping in 95 per cent alcohol and then burning off the alcohol by passing them through the 1406
Tates and. Morse— Bactériologie Tests for Root-Canal Sterility
1407
flame of an alcohol lamp, a sterile towel is removed and placed over the bracket table. O n this sterile towel, there should be placed, in a convenient position, the sterile pan and an alcohol sterilizer with three wells, the center well containing 95 per cent alcohol for flaming instruments and the two outer wells 70 per cent alco hol for holding picks, broaches, files, reamers and any other root-canal instru ments needed; and a white enamel pan 8 by 3 by 2 inches, containing 70 per cent alcohol, for holding mirrors, cotton pliers, burs, plastic instruments, explorers, gut ta-percha instruments, etc. A n alcohol lamp or its equivalent should also be available. Before any supplies are taken from the sterile pan, the tines of the cotton pliers should be dipped in 95 per cent alcohol and passed through the flame. This will prevent contamination of the materials in the sterile pan. Th e tooth requiring treatment is opened with a sterile bur, and a direct full view o f the pulp chamber and canals ob tained.
ty-two hours. T h e broth before incuba tion should be clear. If, after sufficient incubation, the broth appears cloudy, bacterial growth is present. It is not necessary to make further studies to determine the presence or ab sence of organisms. I f, however, further studies are desired, smears m ay be made from the cloudy broth, stained by Gram ’s method and examined with the oil im mersion objective for the type of organ ism present. Blood-agar plants m ay also be made for a more detailed study of organisms. Such a method of bacteriologic check up eliminates the element of chance and raises the standard of root-canal therapy to that of a modern scientific procedure. It also improves the prognosis of the case by giving accurate information on which to determine what the next step in treat ment should be. A fter two consecutive negative bac teriologic check-ups have been made, and other conditions have been fulfilled, the canal or canals are ready to be filled. Failure to secure negative results contra-indicates further root-canal treatment.
BACTERIO LO GIC C H E C K -U P
T H E INCUBATOR
T h e tines of the cotton pliers are flamed, and a sterile J & J paper point is taken from the sterile pan and placed in the canal to be checked; or the point placed in the canal at the last visit of the patient m ay be used. Each culture tube should be labeled, with the patient’s name, number o f tooth, the date, etc. T h e cotton plug in the culture tube is now flamed and removed. T h e neck of the tube is flamed and the paper point from the canal is dropped into the tube. T h e neck o f the culture tube is reflamed and the cotton plug replaced. T h e paper point must be immersed in the culture medium. T h e tube or tubes are now incubated at 3 7 .5 0 C . for from forty-eight to seven
A n expensive thermostatically con trolled incubator is desirable, but not nec essary. A metal or even an insulated wooden box 10 by 12 by 10 inches with a tight fitting door and possibly two re movable shelves, the insertion of which permits reduction of the size o f the box, makes a satisfactory substitute. A n ordi nary oil stove type of metal oven can be adapted very well for use as an incuba tor. There should be two holes in the top of the box, one to admit an electric wire from which to suspend a lamp in the box, the other to permit placing a thermometer in a position to be read from the outside of the box. B y some experimentation with electric bulbs of different sizes, we can find the one which, with the temperature o f the
1408
T h e Journal of the American Dental Association and T h e Dental Cosmos
room fairly constant, will maintain the proper temperature within the box, i.e., 3 7 .5 0 C ., with little or no variation. Such an incubator is employed in the clinical laboratory at the dental school, and we find the temperature in the box can be kept uniformly constant by the use of a 25-w att lamp. W ith the matter o f routine incubation solved in this w ay, there remains the problem of having the proper sterile me dia in tubes o f suitable size so that they can be economically incubated and easily handled at the chair-side. T h e medium which we have found reasonably suc cessful and at the same time easy to prepare is a 1 per cent dextrose infusion broth made up at the laboratory of the bacteriology department of the H arvard M edical School. T o help the bacteriologist whom you might consult in your community to se lect a medium or to prepare a medium especially for your needs, the method of preparation is described. TEC H N IC
For the infusion, steep 400 gm. of fat-free minced beef heart in 1 liter of cold tap water overnight in the ice box. Cook over a free flame, boiling from ten to fifteen minutes. Strain through a wire sieve and adjust the desired pH with tenth normal sodium hy droxide. Then boil thirty minutes over the free flame. Filter hot through paper. Flask in 500 cc. amounts and autoclave at 15 pounds for twenty minutes. To have a final pH of 7.6, 22 cc. of tenth normal sodium hydroxide was added as described above, and the dextrose (1 per cent) added just before placing in the tubes that are to be used for the diagnostic procedure. From our standpoint, that o f showing the presence or absence of organisms on a routine basis, this medium has proved satisfactory. Fo r research work, the brain broth of Rosenow or the glucoseascites medium of the University of M ichigan dental school might be more suitable.
One of the first places to look for help in this matter o f media is the local board of health bacteriologic laboratory, or the laboratory o f a local hospital. T h e broth medium or a 1 per cent agar which is used for the growth of streptococcus or pneumococcus would be a reasonable me dium to try in root canal cases. This medium will probably be more easily handled if it is tubed in small Wassermann tubes, 3 inch by three-eighths inch test tubes. Small tubes o f this size are easier to handle at the chairside and take up less room in the incubator. Th e laboratory should supply the tubes al ready sterilized and ready for use. Th e tubes should be kept where they will not gather dirt, and preferably in a cool place, such as an ice box. T h e latter provision is primarily to reduce evapora tion, with a consequent change in the re action of the medium. I f one is using the tubes fairly frequently so that they will not become too old before using, they will be satisfactory if kept at room tem perature. O f course, it is possible to prepare bac teriologic media in one’s office, but a busy dentist should not take time for it unless it is distinctly a phase of a hobby. It is simply a matter of cooking, but it re quires several ingredients which must be carefully weighed out, and it requires more time than a dentist or even his as sistant should take. I f there is no board of health or hos pital laboratory available which can sup ply the medium conveniently, there is another solution to the problem. O ne can buy media all ready to use, put up in tubes with screw caps and furnished with extra sterile cotton plugs. U sing the same precautions for handling the tubes as with the media prepared locally, the practitioner has only to arrange for incu bation, and return the used tubes to the producer when he orders a fresh supply. M edia can be bought in bulk and the tubes filled and sterilized at the office.
LaG row — Use of Muscle Exercise in Orthodontic Practice This would be a less expensive method, as is likewise the other plan by which the media can be purchased dry and weighed out, dissolved in water and then put in small tubes and sterilized. T h e steriliza tion will require 10 pounds pressure for fifteen minutes in the autoclave or pres sure cooker. Incubation at 3 7 .5 0 C . (9 8 .6 ° F .) should be carried on for seventy-two hours, if nothing appears to be growing in less time. Usually, growth will occur in the first twenty-four hours, but 10 per cent or more of the cultures will not show the development o f organisms for from forty-eight to seventy-two hours, so that for reasonable accuracy this longer period o f incubation must be allowed.
1409
It is rare that, with a positive tube, there will be such slight growth as to offer any difficulty in reading the results. T h e cloudiness is definite. After the tubes have been observed and the results re corded, the tubes should be boiled to prevent danger o f contamination of one self or the office from the organisms which m ay have grown in the tubes. Such a method o f checking the prog ress of root-canal cases by bacteriologic tests is reliable, scientific and practical, and its adoption w ill do much to raise the standards o f treatment for this type of case. T h at it is workable and practical has been proved beyond question and the greater confidence it gives fully justifies its use.
USE OF MUSCLE EXERCISE IN ORTHODONTIC PRACTICE* B y A s a J . L a G r o w , D .D .S., Oak Park,
T
H E use of muscle exercises in or thodontia is to be considered briefly as a therapeutic agent for the pre vention and correction o f malocclusion and as an agent in maintaining occlusion through the improvement of function. In a paper entitled “ Function and R e tention,” Harold J . Noyes1 writes : Th e particular occlusion of an individual is a result of: 1. Th e hereditary pattern or potentiality in growth and development of that individual. 2. The systemic factors which influence the character, formation and function of the body mechanism. 3. The skeletal structural elements including teeth, bone and joints. 4. The soft tissue compris ing muscular, vascular, nervous and connec tive tissue with important accessory stroma and fluids. 5. The interaction of these fac *Presented to the American Board of Or thodontia. Jour. A.D .A. & D . Cos., V ol. 25, September 1938
111.
tors in function. 6. Their response to external stimuli, particularly disease and external pressures. These are very complex and highly synchronized features which in their inter action cannot be easily differentiated. Func tion with respect to dental organs is con cerned essentially with performance and is influenced by all of these factors.
T h e scientific workers in the orthodon tic field are not in entire accord as to the value of muscle exercise or myofunc tional treatment. In an epoch-making contribution on the mechanism of growth of the human face, K eith and Cam pion2 produced evidence that the mechanism is influenced b y the functional state of the pituitary and the gonads. T h e y con clude, however, w i t h : Modem dietary is of a kind which leaves teeth, jaws and muscles of mastication im perfectly exercised. The physical stimuli
I
N the light of modern scientific re search, root-canal therapy can be at tempted only under conditions of strict asepsis and when the progress of treatment is bacteriologically checked. T h e old method of determining the condition of the canal by the absence of odor or moisture can no longer be deemed adequate, in view of our present knowl edge of biologic processes. M ost practitioners have failed to make use of this scientific control of treatment mainly because of the supposed expense involved. It is generally believed that this procedure requires an elaborate equipment plus medical training to in terpret the findings. This is not the case, for already m any modern dental offices are depending on bacteriologic controls in all root-canal cases and are finding that such a procedure does not require expensive equipment or involve compli cated tests. L e t us first consider the clinical re quirements for carrying out the technic, and later the equipment for incubation and the culture material needed. T h e first and most important require ment is that all operations be carried on under strict asepsis, as otherwise the bac teriologic findings have no meaning what ever. This requires, first, a sterile field of operation; that is, a field painted with tincture o f iodine, with the rubber dam in position. A ll instruments to be used should be freshly sterilized and kept aseptic by being placed in a tray containing 70 per From the Harvard Dental School. Jo u r. A .D .A . & D. Cos., Vol. 25, September 1938
cent alcohol or some other suitable steri lizing solution. A sterile pan should be provided, of white enamel, possibly 4 by 5 by 2 inches, and containing cotton pledgets, J & J paper points, sterile gauze, cotton rolls, short pieces of orthodontic wire 26-gage, about 1 or 2 inches long, to be used as diagnostic wires for meas urement of the canal, and two dental towels. T h e pan should be wrapped in a piece of sheeting and fastened with pins. These pans m ay be prepared in the office, several at a time, and, if it is con venient, can be sent to a near-by hospital for autoclaving. T h e sterilization of the pans can be done in the office by using an ordinary pressure cooker with a pressure gage. Tw e n ty pounds pressure maintained for from fifteen to twenty minutes is suffi cient. T h e pans m ay be baked in a gas or electric range oven at 16 0 ° C . (or 3 2 0 ° F .) for one hour and a half. A ll modern gas and electric ovens are equipped with thermostats, which will maintain any de sired temperature. These pans, if prop erly wrapped after sterilization, m ay be kept in the office for some time without danger of contamination. A S E P T IC T EC H N IC
W ith the rubber dam in position and the field painted with tincture of iodine, the pins holding the covering of the sterile pan are carefully removed. W ith cotton pliers, the tines of which have been flamed by dipping in 95 per cent alcohol and then burning off the alcohol by passing them through the 1406
Tates and. Morse— Bactériologie Tests for Root-Canal Sterility
1407
flame of an alcohol lamp, a sterile towel is removed and placed over the bracket table. O n this sterile towel, there should be placed, in a convenient position, the sterile pan and an alcohol sterilizer with three wells, the center well containing 95 per cent alcohol for flaming instruments and the two outer wells 70 per cent alco hol for holding picks, broaches, files, reamers and any other root-canal instru ments needed; and a white enamel pan 8 by 3 by 2 inches, containing 70 per cent alcohol, for holding mirrors, cotton pliers, burs, plastic instruments, explorers, gut ta-percha instruments, etc. A n alcohol lamp or its equivalent should also be available. Before any supplies are taken from the sterile pan, the tines of the cotton pliers should be dipped in 95 per cent alcohol and passed through the flame. This will prevent contamination of the materials in the sterile pan. Th e tooth requiring treatment is opened with a sterile bur, and a direct full view o f the pulp chamber and canals ob tained.
ty-two hours. T h e broth before incuba tion should be clear. If, after sufficient incubation, the broth appears cloudy, bacterial growth is present. It is not necessary to make further studies to determine the presence or ab sence of organisms. I f, however, further studies are desired, smears m ay be made from the cloudy broth, stained by Gram ’s method and examined with the oil im mersion objective for the type of organ ism present. Blood-agar plants m ay also be made for a more detailed study of organisms. Such a method of bacteriologic check up eliminates the element of chance and raises the standard of root-canal therapy to that of a modern scientific procedure. It also improves the prognosis of the case by giving accurate information on which to determine what the next step in treat ment should be. A fter two consecutive negative bac teriologic check-ups have been made, and other conditions have been fulfilled, the canal or canals are ready to be filled. Failure to secure negative results contra-indicates further root-canal treatment.
BACTERIO LO GIC C H E C K -U P
T H E INCUBATOR
T h e tines of the cotton pliers are flamed, and a sterile J & J paper point is taken from the sterile pan and placed in the canal to be checked; or the point placed in the canal at the last visit of the patient m ay be used. Each culture tube should be labeled, with the patient’s name, number o f tooth, the date, etc. T h e cotton plug in the culture tube is now flamed and removed. T h e neck of the tube is flamed and the paper point from the canal is dropped into the tube. T h e neck o f the culture tube is reflamed and the cotton plug replaced. T h e paper point must be immersed in the culture medium. T h e tube or tubes are now incubated at 3 7 .5 0 C . for from forty-eight to seven
A n expensive thermostatically con trolled incubator is desirable, but not nec essary. A metal or even an insulated wooden box 10 by 12 by 10 inches with a tight fitting door and possibly two re movable shelves, the insertion of which permits reduction of the size o f the box, makes a satisfactory substitute. A n ordi nary oil stove type of metal oven can be adapted very well for use as an incuba tor. There should be two holes in the top of the box, one to admit an electric wire from which to suspend a lamp in the box, the other to permit placing a thermometer in a position to be read from the outside of the box. B y some experimentation with electric bulbs of different sizes, we can find the one which, with the temperature o f the
1408
T h e Journal of the American Dental Association and T h e Dental Cosmos
room fairly constant, will maintain the proper temperature within the box, i.e., 3 7 .5 0 C ., with little or no variation. Such an incubator is employed in the clinical laboratory at the dental school, and we find the temperature in the box can be kept uniformly constant by the use of a 25-w att lamp. W ith the matter o f routine incubation solved in this w ay, there remains the problem of having the proper sterile me dia in tubes o f suitable size so that they can be economically incubated and easily handled at the chair-side. T h e medium which we have found reasonably suc cessful and at the same time easy to prepare is a 1 per cent dextrose infusion broth made up at the laboratory of the bacteriology department of the H arvard M edical School. T o help the bacteriologist whom you might consult in your community to se lect a medium or to prepare a medium especially for your needs, the method of preparation is described. TEC H N IC
For the infusion, steep 400 gm. of fat-free minced beef heart in 1 liter of cold tap water overnight in the ice box. Cook over a free flame, boiling from ten to fifteen minutes. Strain through a wire sieve and adjust the desired pH with tenth normal sodium hy droxide. Then boil thirty minutes over the free flame. Filter hot through paper. Flask in 500 cc. amounts and autoclave at 15 pounds for twenty minutes. To have a final pH of 7.6, 22 cc. of tenth normal sodium hydroxide was added as described above, and the dextrose (1 per cent) added just before placing in the tubes that are to be used for the diagnostic procedure. From our standpoint, that o f showing the presence or absence of organisms on a routine basis, this medium has proved satisfactory. Fo r research work, the brain broth of Rosenow or the glucoseascites medium of the University of M ichigan dental school might be more suitable.
One of the first places to look for help in this matter o f media is the local board of health bacteriologic laboratory, or the laboratory o f a local hospital. T h e broth medium or a 1 per cent agar which is used for the growth of streptococcus or pneumococcus would be a reasonable me dium to try in root canal cases. This medium will probably be more easily handled if it is tubed in small Wassermann tubes, 3 inch by three-eighths inch test tubes. Small tubes o f this size are easier to handle at the chairside and take up less room in the incubator. Th e laboratory should supply the tubes al ready sterilized and ready for use. Th e tubes should be kept where they will not gather dirt, and preferably in a cool place, such as an ice box. T h e latter provision is primarily to reduce evapora tion, with a consequent change in the re action of the medium. I f one is using the tubes fairly frequently so that they will not become too old before using, they will be satisfactory if kept at room tem perature. O f course, it is possible to prepare bac teriologic media in one’s office, but a busy dentist should not take time for it unless it is distinctly a phase of a hobby. It is simply a matter of cooking, but it re quires several ingredients which must be carefully weighed out, and it requires more time than a dentist or even his as sistant should take. I f there is no board of health or hos pital laboratory available which can sup ply the medium conveniently, there is another solution to the problem. O ne can buy media all ready to use, put up in tubes with screw caps and furnished with extra sterile cotton plugs. U sing the same precautions for handling the tubes as with the media prepared locally, the practitioner has only to arrange for incu bation, and return the used tubes to the producer when he orders a fresh supply. M edia can be bought in bulk and the tubes filled and sterilized at the office.
LaG row — Use of Muscle Exercise in Orthodontic Practice This would be a less expensive method, as is likewise the other plan by which the media can be purchased dry and weighed out, dissolved in water and then put in small tubes and sterilized. T h e steriliza tion will require 10 pounds pressure for fifteen minutes in the autoclave or pres sure cooker. Incubation at 3 7 .5 0 C . (9 8 .6 ° F .) should be carried on for seventy-two hours, if nothing appears to be growing in less time. Usually, growth will occur in the first twenty-four hours, but 10 per cent or more of the cultures will not show the development o f organisms for from forty-eight to seventy-two hours, so that for reasonable accuracy this longer period o f incubation must be allowed.
1409
It is rare that, with a positive tube, there will be such slight growth as to offer any difficulty in reading the results. T h e cloudiness is definite. After the tubes have been observed and the results re corded, the tubes should be boiled to prevent danger o f contamination of one self or the office from the organisms which m ay have grown in the tubes. Such a method o f checking the prog ress of root-canal cases by bacteriologic tests is reliable, scientific and practical, and its adoption w ill do much to raise the standards o f treatment for this type of case. T h at it is workable and practical has been proved beyond question and the greater confidence it gives fully justifies its use.
USE OF MUSCLE EXERCISE IN ORTHODONTIC PRACTICE* B y A s a J . L a G r o w , D .D .S., Oak Park,
T
H E use of muscle exercises in or thodontia is to be considered briefly as a therapeutic agent for the pre vention and correction o f malocclusion and as an agent in maintaining occlusion through the improvement of function. In a paper entitled “ Function and R e tention,” Harold J . Noyes1 writes : Th e particular occlusion of an individual is a result of: 1. Th e hereditary pattern or potentiality in growth and development of that individual. 2. The systemic factors which influence the character, formation and function of the body mechanism. 3. The skeletal structural elements including teeth, bone and joints. 4. The soft tissue compris ing muscular, vascular, nervous and connec tive tissue with important accessory stroma and fluids. 5. The interaction of these fac *Presented to the American Board of Or thodontia. Jour. A.D .A. & D . Cos., V ol. 25, September 1938
111.
tors in function. 6. Their response to external stimuli, particularly disease and external pressures. These are very complex and highly synchronized features which in their inter action cannot be easily differentiated. Func tion with respect to dental organs is con cerned essentially with performance and is influenced by all of these factors.
T h e scientific workers in the orthodon tic field are not in entire accord as to the value of muscle exercise or myofunc tional treatment. In an epoch-making contribution on the mechanism of growth of the human face, K eith and Cam pion2 produced evidence that the mechanism is influenced b y the functional state of the pituitary and the gonads. T h e y con clude, however, w i t h : Modem dietary is of a kind which leaves teeth, jaws and muscles of mastication im perfectly exercised. The physical stimuli