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Viral hepatitis in relation to dentistry
K N IG H TO N . . . VO LU M E 63, JU L Y 1961 • 37/21
24. Wilson, R. T .; Phillips, R. W ., and Norman, R. D. Influence of certain condensation procedures upon the mercury content of' amalgam restorations. J . D. Res. 36:458 June 1957. 25. Flag, J . F. M etallic pastes for filling teeth. Am . J . D. Sc. 4:210, 1844. 26. Sweeney, J . T. Am algam manipulation: manual vs. mechanical aids. Part II. Comparison of clinical applications. J .A .D .A . 27:1940 Dec. 1940. 27. Swartz, M. L., and Phillips, R. W . Study of am al gam condensation procedures with emphasis on the residual mercury content of the increments. I. Strenqth, flow, and dimensional change. J . D. Res. 33:12 Feb. 1954. 28. Skinner, E. W ., and Phillips, R. W . Science of dental materials, ed. 5. Philadelphia, W . B. Saunders C o ., I960, chapter 21. 29. Swartz, M . L .; Phillips, R. W ., and El Tannir, M. D. Tarnish of certain dental alloys. J . D. Res. 37:837 Sept.-O ct. 1958.
30. Roper, L. H . Restorations with amalgam in the arm y: an evaluation and analysis. J .A .D .A . 34:443 A p ril I, 1947. 31. Moss, R. P. Am algam failures. U. S. Armed Forces M. J . 4:735 May 1953. 32. Craw ford, W . H ., and Larson, J . H . Residual mer cury determination process. J . D. Res. 34:313 June 1955. 33. Phillips, R. W ., and others. C lin ical observations on amalgam with known physical properties—final re port. J .A .D .A . 32:324 March 1945. 34. W ilkinson, E. G ., and Haack, D. C . Study of the fatigue characteristics of silver am algam . J . D. Res. 37:136 Feb. 1958. 35. Mahler, D. B. Analysis of stresses in a dental amalgam restoration. J . D. Res. 37:516 June 1958. 36. Eames, W . B. Preparation and condensation of amalgam with a low mercury-alloy ratio. J .A .D .A . 58:78 A p ril 1959.
Viral hepatitis in relation to dentistry
Holmes T. Knighton * D.D.S., Richmond, Va.
Case reports provide good circumstantial evidence that some dentists may have transmitted viral hepatitis from patient to patient. The possibility of transmitting viral hepatitis should influence dentists to use every possible precaution to ster ilize all cutting instruments that may be contaminated with blood before the in struments are reused. It is suggested that instruments capable of transferring blood from one patient to another be sterilized by autoclaving at 121°C. for 15 minutes or by exposure to dry heat at a tempera ture of 160°C. (320°F .) for one hour. Exposure to- boiling water (1 0 0 °C .) for 30 minutes should be considered mini mum treatment for safety in disinfecting penetrating instruments.
The term “ viral hepatitis” generally re fers to diseases caused by two or possibly more filtrable infectious agents. These
agents produce a systemic disease with a characteristic type of liver damage; how ever, jaundice is not a necessary condition for diagnosis.1 The causative viruses are not yet identifiable by cultural or spe cific serological methods, thus available knowledge of the diseases and causative agents has been obtained from clinical observations, including experiments with human volunteers. The exact relationship between the two agents causing viral hepatitis is not fully understood. However, recognized differences are sufficient to support the view that the agents produce somewhat similar pathologic conditions but differ in epidemiologic and immunologic charac teristics. These viral agents are com monly referred to as “ infectious hepatitis virus” and “ serum hepatitis virus,” but these names are not entirely satisfactory since both of the viruses may be trans mitted by parenteral injections. In view of this the term “ Virus A ” and “ Virus B” are often used for infectious hepatitis
38/22 • TH E JO U R N A L O F TH E A M E R IC A N DEN TAL A 5 SO C IA TJO N
virus and serum hepatitis virus respec tively.1, 2 In an excellent presentation on viral hepatitis, Eichenwald and Mosley1 in clude the following concise differentiation between the two viral agencies: (1) Virus A : This agent is responsible for cases of the disease recognized chiefly on epi demiologic grounds as infectious or epidemic hepatitis. This form of the disease has an in cubation period of from 10 to 50 days, with an average of about 30 days. The virus is known to be present in the feces and blood during the acute stage and in the blood during the incubation period. The feces and blood are infectious when administered by oral and parenteral routes. (2) Virus B: This agent accounts for the illness formerly called homologous serus hepa titis, transfusion jaundice, postvaccinal jaun dice, postinoculation jaundice, and delayed arseno-therapy jaundice. This disease has an incubation period of 60 to 160 days. The virus has been demonstrated to be present in the blood, but not the pharyngeal secretions, urine or feces. Blood or blood fractions are infectious to others only when administered parenterally. POSSIBLE ROLE OF DENTIST IN T R AN SM ISSIO N
Since this presentation is chiefly con cerned with a consideration of the pos sible role of the dentist in transmission o f viral hepatitis, only the following phases will be considered: (1) mode of transmission; (2) amount needed for in fection; (3) resistance of the virus to physical and chefnical disinfecting agents, and (4) evidence for transmission by dental procedures. M ode of Transmission • Virus A (infec tious hepatitis virus) appears in feces during the preicteric phase of illness and persists for 1 to 2 weeks after onset of jaundice in typical cases in adults.1 There is evidence of a fecal to oral route includ ing contamination of water, food and milk.1 There is also the possibility that insects may play a role in the mechanical transmission in the fecal to oral route. Virus A may occur in the blood as early as two weeks prior to the onset of jaun
dice, and blood or blood products ob tained during these periods are infective for others if introduced parenterally.1 The only proved means of transmitting Virus B (serum hepatitis virus) is by parenteral introduction.3 Patients with Virus B infections have a viremia which may begin as early as three months prior to onset of symptoms and persist into the acute phase of the disease.1 Further more, either virus may occur in the blood of individuals who have no history of hepatitis or any symptoms suggestive of acute or chronic illness. This carrier state may persist for at least 1 to 5 years, and the carrier rates for Virus B have been estimated at 0.5 per cent of all individuals.1 Amount Needed for Infection • It has been shown that as little as 0.01 ml. of blood from a patient with infectious hepatitis due to Virus A and only 0.00004 ml. from patients with serum hepatitis (Virus B) have produced disease in hu man volunteers.1 In view o f the latter, along with experimental evidence indicat ing the ease with which needles and syringes become contaminated with blood after injections,4,5 both dentists and phy sicians should be concerned with the pos sibility o f transmitting viral hepatitis. Resistance to Disinfecting Agents • Since neither Virus A nor Virus B have been isolated in cultures, or by animal inocu lation, relatively little data are available as to their degree of resistance to physi cal and chemical agents of destruction. It has been reported that Virus B survives 60°G. water for one hour, but may be inactivated by a similar temperature for ten hours.6 Virus B . is not inactivated in serum containing thimerosal (Merthiolate) in concentrations of 1/2000 or in 0.2 per cent concentration o f tricresol.7 Virus A is known to survive 1 ppm chlorine in water for 30 minutes but is attenuated by 15 ppm.5 Nitrogen mustard in a con
K N IG H TO N . . . VO LU M E 63, JU L Y 1961 • 39/23
centration o f 500 mg. per milliliter failed to inactivate a strain of Virus B though such concentrations did inactivate such other viruses as influenza.8 Indirect evidence of the relative resist ance of Virus B is noted by Salaman and associates9 in a discussion of two technics for the disinfection o f syringes and needles used for treatment of syphilis. In the first technic needles and syringes were boiled at the start of each day. After in jection of the medicament, the needle was removed and boiled and the syringe was rinsed under tap water, and if an adequate number o f syringes were avail able, they were left for a short time in industrial alcohol, biniodide of mercury or weak saponated cresol solution (Lys o l). The syringe was then fitted with a freshly boiled needle and used for an other injection. After this procedure, 37 per cent of 67 patients treated for 120 days and 68 per cent o f 56 patients treated for 180 days developed viral hepa titis. After this experience, all needles and syringes were heated at 150 to 160°C. dry heat for one hour before giv ing injections. The incidence of hepa titis was reduced to 1 (2.7 per cent) of 36 patients treated 120 days and to 1 (5.6 per cent) o f 18 treated 180 days. Further evidence is noted in a report of a serious outbreak of homologous serum hepatitis in 1946-1947 involving 112 patients of one physician, and includ ing 12 deaths. It was stated that because of the large numbers of individuals treated by this physician, he often used only four minutes for boiling instru ments.10 In a comprehensive consideration of the problem of viral hepatitis infections, Perkins11 states that the commonly used methods of “ sterilizing” needles, syringes and lancets by brief exposure to boiling water or immersion in chemical disinfect ants are recognized as inadequate for the destruction of the virus. Perkins also stresses that the National Institutes of Health stipulate that apparatus and in
struments capable of transmitting serum hepatitis from one person to another be heat sterilized by autoclaving 30 minutes at 121°C. (15 lb .), by dry heat for two hours at 170°C. or by boiling in water for 30 minutes. Eichenwald and Mosley1 feel that from epidemiologic reports it seems probable that sterilization by 160°C. dry heat for one hour may be adequate. The necessity o f sufficiently high tem perature, as previously mentioned, along with doubt as to effectiveness of chemi cal disinfectants, for killing hepatitis vi ruses on instruments, has also been stressed by W H O Expert Cofltimittee on Hepa titis.2 In a further consideration of chem ical disinfectants, it has been mentioned by Kersten12 that even though there were chemical disinfectants capable of destroy ing the viruses o f hepatitis, this type of sterilization is not acceptable for hypo dermic needles. The small lumen of the conventional local anesthetic needle very often traps air that prevents the liquid disinfectant from penetrating the entire length of the needle. Evidence of the latter assumption has been noted in both reported13 and unreported studies in the author’s laboratories. In these experi ments sterile crosscut fissure dental burs were contaminated with cultures of Staphylococcus aureus. Earlier experi ments showed that these organisms failed to survive for five minutes if placed di rectly into the test chemicals, yet on the dental burs the same strains of bacteria were often viable after 5 to 15 minutes exposure to the chemicals. On the other hand, similar contaminated burs were in variably sterilized if placed in 100°C. water for five minutes. These experiments suggest the difficulty of killing all organ isms in cracks and crevices of instruments with chemicals. Evidence of Transmission Through D en tal Procedures • Because of the long and varied incubation periods it is difficult to prove that a given injection, or series of
40/24 • TH E JO U R N A L O F TH E A M ER IC A N DEN TAL A S S O C IA T IO N
injections, accounted for a case of hepa titis due to either Virus A or Virus B. On the other hand, since Virus B is probably transmitted only by parenteral introduc tion, there is more reason to suspect a given dentist or physician if a patient received injections only from one doctor, and then develops viral hepatitis within the probable limits of the incubation stage of the disease. Thompson and associates14 reviewed 203 cases of viral hepatitis in patients treated in one hospital and found that four (2 per cent) developed symptoms between 26 to 120 days after injections of anesthetics and extraction of teeth. These authors were unable to determine the method of sterilization used by the dentists. In the same report, viral hepa titis was noted in one patient out o f 208 who had been treated by one dentist 64 days prior to the dentist’s admission to the hospital as a viral hepatitis patient. It is of interest to note that the latter dentist autoclaved all instruments before use on patients. He did, however, have eczematoid dermatitis on his hands and although he wore autoclaved gloves, it was still thought that the dermatitis was a possible reason for transmission. Thom p son and associates concluded that, (1) although occurrences o f viral hepatitis after dental procedures are unusual, they are not rare, and (2) the likelihood of a dentist with the disease transmitting it to a patient is small. In an article on occurrence of serum hepatitis in U. S. troops in Germany, Evans16 includes two soldiers who had a history o f dental operations prior to de velopment of this disease. One of the soldiers also had a history of an injection of penicillin and the other, of removal of sutures from his leg in addition to dental operations. The most impressive evidence has been reported by Foley and Gutheim16 in a survey o f patients discharged from the medical service of a hospital. The sur vey covered a two-year period and in
cluded 57 patients with viral hepatitis. Seven of the patients were considered to have serum hepatitis as a result of blood or plasma transfusions. The remaining 50 patients ordinarily would have been considered to have infectious hepatitis. Fifteen o f them, however, gave a history of an injection by a dentist during the preceding 1 to 6 months. Thirteen had had injections prior to the extraction of teeth and two had had injections in con nection with cavity preparations. In ad dition, two of the 51 patients had re ceived procaine and penicillin injections simultaneously. The authors state that the evidence supported the diagnosis of serum hepatitis as a result o f the dental work. “ It is unlikely,” they conclude, “ that such a large percentage of hepa titis patients could have had injections by a dentist just by chance.” DISCU SSION AND SUM M ARY
The preceding case reports are not ab solutely conclusive proof of the dentist’ s guilt in transmitting viral hepatitis in fection because it is possible that other injections may have been made during the long incubation periods. These re ports, however, do offer very good cir cumstantial evidence. Furthermore, be cause of the long and variable incubation periods, it is quite possible that dentists may be responsible for transmission of a number of unreported instances of viral hepatitis. The probability, or even remote pos sibility, o f transmitting Virus A or Virus B should influence dentists to use every possible precaution to sterilize all instru ments capable of transferring blood or blood products from one patient to an other. Although the use of needles and syringes is the most likely avenue of such transfers, it should be remembered that instruments such as scalpels, forceps, peri odontal instruments and others that are used to penetrate tissues are always p o tential carriers o f the viruses in blood or
K N IG H TO N . . . V O LU M E 63, JU L Y 1961 • 41/25
blood products unless they are adequately sterilized. In addition to contaminated instru ments, the use of a cartridge of anesthetic for injection into more than one patient must be condemned as a definite hazard. Results of a survey made by Zinner and Streitfeld18 indicate that the latter may have occurred much too often in dental offices. In reference to instruments we agree with an editorial comment by Eisenbud : 17 “ In the absence of definite and final knowledge regarding the steriliza tion requirements for this virus, the tech nic recommended by most microbiologists at this time for needles, syringes and cutting instruments is autoclaving. In its absence, boiling for a period of 30 min utes is acceptable. Sterilization by chem ical means is unacceptable.”
This article was prepared at the request of the Coun cil on Dental Therapeutics. *Departments of dental ^research and m icrobioloqy. M edical Co lleg e pf V irginia. 1. Eichenwald, H . F ., and M osley, J . W . Viral hepa titis, clinical and public health aspects. Public Health Service Publication No. 435. Washington, D .C ., U. S. Government Printing O ffice, 1959. 2. Expert Committee on H e p a titis. W orld Health Organization Technical Report Series No. 62. March, 1953.
3. Smith, D. T., and Conant, N. F. Zinsser's micro biology, ed. 12. New York, Appleton-Century-Crofts, Inc., I960, p. 768. 4. Streitfeld, M . M ., and Zinner, D. D. M icrobiologic hazards of local dental anesthesia. II. Pilot study of involuntary aspiration of bacteria into hypodermic needles and anesthetic cartridges after injection. J .A .D .A . 57:657 Nov. 1958. 5. Topleyt W . W . C ., and W ilson, G . S. Topley and W ilson's principles of bacteriology and immunity, ed. 4. G . S. W ilson and A . A . Miles, eds.Baltim ore,W il liams & W ilkins C o ., 1955, p. 2207. 6. Havens, J r ., W . P. H epatitis, yellow fever and dengue. Ann. Rev. M icrobiol. 8:289, 1954. 7. Havens, J r ., W . P., and Paul, J . R. Viral and rickettsial infections of man, ed. 3. T . M. Rivers and F. L. Horsfall, eds. Philadelphia, J . B. Lippincott C o ., 1959, chapter 27. 8. Drake, M . E., and others. Effect of nitrogen mus tard on virus of serum hepatitis in whole blood. Proc. Soc. Exper. Biol. & M ed. 80:310 June 1952. 9. Salaman, M. H ., and others. Prevention of jaun dice resulting from antisyphilic treatment. Lancet 2:7 Ju ly I, 1944. 10. Foreign letters. Epidemic of homologous serum hepatitis. J .A .M .A . 137:209 May 8, 1948. 11. Perkins, J . J . Principles and methods of steriliza tion. Springfield, Charles C Thomas, 1954, p. 43. 12. Kersten, R. B. Dentists and infectious hepatitis. (E d .) J . Michigan D. A . 41:308 Nov. 1959. 13. Knighton, H . T. Studies on the use of chemical antiseptics ana germicides in dentistry. Washington Univ. D. J . 16:123 May 1950. 14. Thompson, J r ., J . L., and others. Transmission of viral hepatitis by dental procedures. J . M. A . Alabam a 23:45 A u g . 1953. 15. Evans, A . S. Serum hepatitis in U .S . troops in Germ any. Proc. Soc. Exper. Biol. & Med. 75:809 Dec. 1950. 16. Foley, F. E., and Gutheim, R. N. Serum hepatitis followinq dental procedures: a presentation of 15 cases including three fata litie s. Ann. Int. Med. 45:369 Sept. 1956. 17. Eisenbud, Leon. Serum hepatitis in dental pa tients. (E d .) New York J . Den. 27:177 May 1957. 18. Zinner, D. D., and Streitfeld, M . M . M icrobiologic hazards of local dental anesthesia. 1. State-wide survey of procedures in common practice. J .A .D .A . 56:508 A p ril 1958.
Organization • The difference between throwing out ideas and writing a well organized book may be compared to the difference between casual flirtations and a responsible marriage. George Sarton. Notes on the Reviewing of Learned Books. Science 131:1186 April 22, 1960.
24. Wilson, R. T .; Phillips, R. W ., and Norman, R. D. Influence of certain condensation procedures upon the mercury content of' amalgam restorations. J . D. Res. 36:458 June 1957. 25. Flag, J . F. M etallic pastes for filling teeth. Am . J . D. Sc. 4:210, 1844. 26. Sweeney, J . T. Am algam manipulation: manual vs. mechanical aids. Part II. Comparison of clinical applications. J .A .D .A . 27:1940 Dec. 1940. 27. Swartz, M. L., and Phillips, R. W . Study of am al gam condensation procedures with emphasis on the residual mercury content of the increments. I. Strenqth, flow, and dimensional change. J . D. Res. 33:12 Feb. 1954. 28. Skinner, E. W ., and Phillips, R. W . Science of dental materials, ed. 5. Philadelphia, W . B. Saunders C o ., I960, chapter 21. 29. Swartz, M . L .; Phillips, R. W ., and El Tannir, M. D. Tarnish of certain dental alloys. J . D. Res. 37:837 Sept.-O ct. 1958.
30. Roper, L. H . Restorations with amalgam in the arm y: an evaluation and analysis. J .A .D .A . 34:443 A p ril I, 1947. 31. Moss, R. P. Am algam failures. U. S. Armed Forces M. J . 4:735 May 1953. 32. Craw ford, W . H ., and Larson, J . H . Residual mer cury determination process. J . D. Res. 34:313 June 1955. 33. Phillips, R. W ., and others. C lin ical observations on amalgam with known physical properties—final re port. J .A .D .A . 32:324 March 1945. 34. W ilkinson, E. G ., and Haack, D. C . Study of the fatigue characteristics of silver am algam . J . D. Res. 37:136 Feb. 1958. 35. Mahler, D. B. Analysis of stresses in a dental amalgam restoration. J . D. Res. 37:516 June 1958. 36. Eames, W . B. Preparation and condensation of amalgam with a low mercury-alloy ratio. J .A .D .A . 58:78 A p ril 1959.
Viral hepatitis in relation to dentistry
Holmes T. Knighton * D.D.S., Richmond, Va.
Case reports provide good circumstantial evidence that some dentists may have transmitted viral hepatitis from patient to patient. The possibility of transmitting viral hepatitis should influence dentists to use every possible precaution to ster ilize all cutting instruments that may be contaminated with blood before the in struments are reused. It is suggested that instruments capable of transferring blood from one patient to another be sterilized by autoclaving at 121°C. for 15 minutes or by exposure to dry heat at a tempera ture of 160°C. (320°F .) for one hour. Exposure to- boiling water (1 0 0 °C .) for 30 minutes should be considered mini mum treatment for safety in disinfecting penetrating instruments.
The term “ viral hepatitis” generally re fers to diseases caused by two or possibly more filtrable infectious agents. These
agents produce a systemic disease with a characteristic type of liver damage; how ever, jaundice is not a necessary condition for diagnosis.1 The causative viruses are not yet identifiable by cultural or spe cific serological methods, thus available knowledge of the diseases and causative agents has been obtained from clinical observations, including experiments with human volunteers. The exact relationship between the two agents causing viral hepatitis is not fully understood. However, recognized differences are sufficient to support the view that the agents produce somewhat similar pathologic conditions but differ in epidemiologic and immunologic charac teristics. These viral agents are com monly referred to as “ infectious hepatitis virus” and “ serum hepatitis virus,” but these names are not entirely satisfactory since both of the viruses may be trans mitted by parenteral injections. In view of this the term “ Virus A ” and “ Virus B” are often used for infectious hepatitis
38/22 • TH E JO U R N A L O F TH E A M E R IC A N DEN TAL A 5 SO C IA TJO N
virus and serum hepatitis virus respec tively.1, 2 In an excellent presentation on viral hepatitis, Eichenwald and Mosley1 in clude the following concise differentiation between the two viral agencies: (1) Virus A : This agent is responsible for cases of the disease recognized chiefly on epi demiologic grounds as infectious or epidemic hepatitis. This form of the disease has an in cubation period of from 10 to 50 days, with an average of about 30 days. The virus is known to be present in the feces and blood during the acute stage and in the blood during the incubation period. The feces and blood are infectious when administered by oral and parenteral routes. (2) Virus B: This agent accounts for the illness formerly called homologous serus hepa titis, transfusion jaundice, postvaccinal jaun dice, postinoculation jaundice, and delayed arseno-therapy jaundice. This disease has an incubation period of 60 to 160 days. The virus has been demonstrated to be present in the blood, but not the pharyngeal secretions, urine or feces. Blood or blood fractions are infectious to others only when administered parenterally. POSSIBLE ROLE OF DENTIST IN T R AN SM ISSIO N
Since this presentation is chiefly con cerned with a consideration of the pos sible role of the dentist in transmission o f viral hepatitis, only the following phases will be considered: (1) mode of transmission; (2) amount needed for in fection; (3) resistance of the virus to physical and chefnical disinfecting agents, and (4) evidence for transmission by dental procedures. M ode of Transmission • Virus A (infec tious hepatitis virus) appears in feces during the preicteric phase of illness and persists for 1 to 2 weeks after onset of jaundice in typical cases in adults.1 There is evidence of a fecal to oral route includ ing contamination of water, food and milk.1 There is also the possibility that insects may play a role in the mechanical transmission in the fecal to oral route. Virus A may occur in the blood as early as two weeks prior to the onset of jaun
dice, and blood or blood products ob tained during these periods are infective for others if introduced parenterally.1 The only proved means of transmitting Virus B (serum hepatitis virus) is by parenteral introduction.3 Patients with Virus B infections have a viremia which may begin as early as three months prior to onset of symptoms and persist into the acute phase of the disease.1 Further more, either virus may occur in the blood of individuals who have no history of hepatitis or any symptoms suggestive of acute or chronic illness. This carrier state may persist for at least 1 to 5 years, and the carrier rates for Virus B have been estimated at 0.5 per cent of all individuals.1 Amount Needed for Infection • It has been shown that as little as 0.01 ml. of blood from a patient with infectious hepatitis due to Virus A and only 0.00004 ml. from patients with serum hepatitis (Virus B) have produced disease in hu man volunteers.1 In view o f the latter, along with experimental evidence indicat ing the ease with which needles and syringes become contaminated with blood after injections,4,5 both dentists and phy sicians should be concerned with the pos sibility o f transmitting viral hepatitis. Resistance to Disinfecting Agents • Since neither Virus A nor Virus B have been isolated in cultures, or by animal inocu lation, relatively little data are available as to their degree of resistance to physi cal and chemical agents of destruction. It has been reported that Virus B survives 60°G. water for one hour, but may be inactivated by a similar temperature for ten hours.6 Virus B . is not inactivated in serum containing thimerosal (Merthiolate) in concentrations of 1/2000 or in 0.2 per cent concentration o f tricresol.7 Virus A is known to survive 1 ppm chlorine in water for 30 minutes but is attenuated by 15 ppm.5 Nitrogen mustard in a con
K N IG H TO N . . . VO LU M E 63, JU L Y 1961 • 39/23
centration o f 500 mg. per milliliter failed to inactivate a strain of Virus B though such concentrations did inactivate such other viruses as influenza.8 Indirect evidence of the relative resist ance of Virus B is noted by Salaman and associates9 in a discussion of two technics for the disinfection o f syringes and needles used for treatment of syphilis. In the first technic needles and syringes were boiled at the start of each day. After in jection of the medicament, the needle was removed and boiled and the syringe was rinsed under tap water, and if an adequate number o f syringes were avail able, they were left for a short time in industrial alcohol, biniodide of mercury or weak saponated cresol solution (Lys o l). The syringe was then fitted with a freshly boiled needle and used for an other injection. After this procedure, 37 per cent of 67 patients treated for 120 days and 68 per cent o f 56 patients treated for 180 days developed viral hepa titis. After this experience, all needles and syringes were heated at 150 to 160°C. dry heat for one hour before giv ing injections. The incidence of hepa titis was reduced to 1 (2.7 per cent) of 36 patients treated 120 days and to 1 (5.6 per cent) o f 18 treated 180 days. Further evidence is noted in a report of a serious outbreak of homologous serum hepatitis in 1946-1947 involving 112 patients of one physician, and includ ing 12 deaths. It was stated that because of the large numbers of individuals treated by this physician, he often used only four minutes for boiling instru ments.10 In a comprehensive consideration of the problem of viral hepatitis infections, Perkins11 states that the commonly used methods of “ sterilizing” needles, syringes and lancets by brief exposure to boiling water or immersion in chemical disinfect ants are recognized as inadequate for the destruction of the virus. Perkins also stresses that the National Institutes of Health stipulate that apparatus and in
struments capable of transmitting serum hepatitis from one person to another be heat sterilized by autoclaving 30 minutes at 121°C. (15 lb .), by dry heat for two hours at 170°C. or by boiling in water for 30 minutes. Eichenwald and Mosley1 feel that from epidemiologic reports it seems probable that sterilization by 160°C. dry heat for one hour may be adequate. The necessity o f sufficiently high tem perature, as previously mentioned, along with doubt as to effectiveness of chemi cal disinfectants, for killing hepatitis vi ruses on instruments, has also been stressed by W H O Expert Cofltimittee on Hepa titis.2 In a further consideration of chem ical disinfectants, it has been mentioned by Kersten12 that even though there were chemical disinfectants capable of destroy ing the viruses o f hepatitis, this type of sterilization is not acceptable for hypo dermic needles. The small lumen of the conventional local anesthetic needle very often traps air that prevents the liquid disinfectant from penetrating the entire length of the needle. Evidence of the latter assumption has been noted in both reported13 and unreported studies in the author’s laboratories. In these experi ments sterile crosscut fissure dental burs were contaminated with cultures of Staphylococcus aureus. Earlier experi ments showed that these organisms failed to survive for five minutes if placed di rectly into the test chemicals, yet on the dental burs the same strains of bacteria were often viable after 5 to 15 minutes exposure to the chemicals. On the other hand, similar contaminated burs were in variably sterilized if placed in 100°C. water for five minutes. These experiments suggest the difficulty of killing all organ isms in cracks and crevices of instruments with chemicals. Evidence of Transmission Through D en tal Procedures • Because of the long and varied incubation periods it is difficult to prove that a given injection, or series of
40/24 • TH E JO U R N A L O F TH E A M ER IC A N DEN TAL A S S O C IA T IO N
injections, accounted for a case of hepa titis due to either Virus A or Virus B. On the other hand, since Virus B is probably transmitted only by parenteral introduc tion, there is more reason to suspect a given dentist or physician if a patient received injections only from one doctor, and then develops viral hepatitis within the probable limits of the incubation stage of the disease. Thompson and associates14 reviewed 203 cases of viral hepatitis in patients treated in one hospital and found that four (2 per cent) developed symptoms between 26 to 120 days after injections of anesthetics and extraction of teeth. These authors were unable to determine the method of sterilization used by the dentists. In the same report, viral hepa titis was noted in one patient out o f 208 who had been treated by one dentist 64 days prior to the dentist’s admission to the hospital as a viral hepatitis patient. It is of interest to note that the latter dentist autoclaved all instruments before use on patients. He did, however, have eczematoid dermatitis on his hands and although he wore autoclaved gloves, it was still thought that the dermatitis was a possible reason for transmission. Thom p son and associates concluded that, (1) although occurrences o f viral hepatitis after dental procedures are unusual, they are not rare, and (2) the likelihood of a dentist with the disease transmitting it to a patient is small. In an article on occurrence of serum hepatitis in U. S. troops in Germany, Evans16 includes two soldiers who had a history o f dental operations prior to de velopment of this disease. One of the soldiers also had a history of an injection of penicillin and the other, of removal of sutures from his leg in addition to dental operations. The most impressive evidence has been reported by Foley and Gutheim16 in a survey o f patients discharged from the medical service of a hospital. The sur vey covered a two-year period and in
cluded 57 patients with viral hepatitis. Seven of the patients were considered to have serum hepatitis as a result of blood or plasma transfusions. The remaining 50 patients ordinarily would have been considered to have infectious hepatitis. Fifteen o f them, however, gave a history of an injection by a dentist during the preceding 1 to 6 months. Thirteen had had injections prior to the extraction of teeth and two had had injections in con nection with cavity preparations. In ad dition, two of the 51 patients had re ceived procaine and penicillin injections simultaneously. The authors state that the evidence supported the diagnosis of serum hepatitis as a result o f the dental work. “ It is unlikely,” they conclude, “ that such a large percentage of hepa titis patients could have had injections by a dentist just by chance.” DISCU SSION AND SUM M ARY
The preceding case reports are not ab solutely conclusive proof of the dentist’ s guilt in transmitting viral hepatitis in fection because it is possible that other injections may have been made during the long incubation periods. These re ports, however, do offer very good cir cumstantial evidence. Furthermore, be cause of the long and variable incubation periods, it is quite possible that dentists may be responsible for transmission of a number of unreported instances of viral hepatitis. The probability, or even remote pos sibility, o f transmitting Virus A or Virus B should influence dentists to use every possible precaution to sterilize all instru ments capable of transferring blood or blood products from one patient to an other. Although the use of needles and syringes is the most likely avenue of such transfers, it should be remembered that instruments such as scalpels, forceps, peri odontal instruments and others that are used to penetrate tissues are always p o tential carriers o f the viruses in blood or
K N IG H TO N . . . V O LU M E 63, JU L Y 1961 • 41/25
blood products unless they are adequately sterilized. In addition to contaminated instru ments, the use of a cartridge of anesthetic for injection into more than one patient must be condemned as a definite hazard. Results of a survey made by Zinner and Streitfeld18 indicate that the latter may have occurred much too often in dental offices. In reference to instruments we agree with an editorial comment by Eisenbud : 17 “ In the absence of definite and final knowledge regarding the steriliza tion requirements for this virus, the tech nic recommended by most microbiologists at this time for needles, syringes and cutting instruments is autoclaving. In its absence, boiling for a period of 30 min utes is acceptable. Sterilization by chem ical means is unacceptable.”
This article was prepared at the request of the Coun cil on Dental Therapeutics. *Departments of dental ^research and m icrobioloqy. M edical Co lleg e pf V irginia. 1. Eichenwald, H . F ., and M osley, J . W . Viral hepa titis, clinical and public health aspects. Public Health Service Publication No. 435. Washington, D .C ., U. S. Government Printing O ffice, 1959. 2. Expert Committee on H e p a titis. W orld Health Organization Technical Report Series No. 62. March, 1953.
3. Smith, D. T., and Conant, N. F. Zinsser's micro biology, ed. 12. New York, Appleton-Century-Crofts, Inc., I960, p. 768. 4. Streitfeld, M . M ., and Zinner, D. D. M icrobiologic hazards of local dental anesthesia. II. Pilot study of involuntary aspiration of bacteria into hypodermic needles and anesthetic cartridges after injection. J .A .D .A . 57:657 Nov. 1958. 5. Topleyt W . W . C ., and W ilson, G . S. Topley and W ilson's principles of bacteriology and immunity, ed. 4. G . S. W ilson and A . A . Miles, eds.Baltim ore,W il liams & W ilkins C o ., 1955, p. 2207. 6. Havens, J r ., W . P. H epatitis, yellow fever and dengue. Ann. Rev. M icrobiol. 8:289, 1954. 7. Havens, J r ., W . P., and Paul, J . R. Viral and rickettsial infections of man, ed. 3. T . M. Rivers and F. L. Horsfall, eds. Philadelphia, J . B. Lippincott C o ., 1959, chapter 27. 8. Drake, M . E., and others. Effect of nitrogen mus tard on virus of serum hepatitis in whole blood. Proc. Soc. Exper. Biol. & M ed. 80:310 June 1952. 9. Salaman, M. H ., and others. Prevention of jaun dice resulting from antisyphilic treatment. Lancet 2:7 Ju ly I, 1944. 10. Foreign letters. Epidemic of homologous serum hepatitis. J .A .M .A . 137:209 May 8, 1948. 11. Perkins, J . J . Principles and methods of steriliza tion. Springfield, Charles C Thomas, 1954, p. 43. 12. Kersten, R. B. Dentists and infectious hepatitis. (E d .) J . Michigan D. A . 41:308 Nov. 1959. 13. Knighton, H . T. Studies on the use of chemical antiseptics ana germicides in dentistry. Washington Univ. D. J . 16:123 May 1950. 14. Thompson, J r ., J . L., and others. Transmission of viral hepatitis by dental procedures. J . M. A . Alabam a 23:45 A u g . 1953. 15. Evans, A . S. Serum hepatitis in U .S . troops in Germ any. Proc. Soc. Exper. Biol. & Med. 75:809 Dec. 1950. 16. Foley, F. E., and Gutheim, R. N. Serum hepatitis followinq dental procedures: a presentation of 15 cases including three fata litie s. Ann. Int. Med. 45:369 Sept. 1956. 17. Eisenbud, Leon. Serum hepatitis in dental pa tients. (E d .) New York J . Den. 27:177 May 1957. 18. Zinner, D. D., and Streitfeld, M . M . M icrobiologic hazards of local dental anesthesia. 1. State-wide survey of procedures in common practice. J .A .D .A . 56:508 A p ril 1958.
Organization • The difference between throwing out ideas and writing a well organized book may be compared to the difference between casual flirtations and a responsible marriage. George Sarton. Notes on the Reviewing of Learned Books. Science 131:1186 April 22, 1960.