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A laboratory for teaching oral-surgical technique
Journal of Dentistry, 13, Na 4, 1985, pp 318-322
A laboratory technique G. C. Stacy, Depa/tment Westmead
for teaching
BDS, FDSRCS, DOrth KS, of Oral Medicine
Dental
Primed in Greaf Britain
and
oral-surgical
FRACDS
Oral Surgery
Clinical School, Westmead
The University
of Sydney
and
Hospital, NSW
ABSTRACT A special-purpose laboratory designed to improve the efticiency of simulated teaching of oral-surgical techniques at both undergraduate and graduate levels is described The laboratory is recommended because it has simplified further the staging of oral-surgical-technique teaching The possible risk of infections from the use of animal tissue in this type of laboratory is also discussed.
INTRODUCTION Teaching oral-surgical technique on pig’s heads was originally undertaken with the prepared jaw sitting free in a metal tray (Moore et al., 1965). Subsequently, specially designed laboratory clamps were developed (Stacy, 1966, 1967 b) which allowed for greater safety and ease of management of the specimens during teaching sessions in a prosthetic laboratory. A self-contained laboratory entirely devoted to animal head (pig) and other practical demonstrations before oral-surgical clinical work was foreshadowed in 1966 as a highly efftcient workshop for undergraduate and graduate university education (Stacy, 1966). This complete concept has now been incorporated into the new teaching facility for the Faculty of Dentistry, University of Sydney within the Department of Oral and Maxillo-Facial Surgery, Westmead Dental Clinical School, Westmead, NSW and is proving to be a powerful addition to the oral-surgical teaching programme. The value of having simulated oral-surgical exercises presented in an orderly sequence in a suitably equipped laboratory has also been recognized by others (Bonnette and Hayward, 1969). The content of each teaching session is tailored to the student requirements but there is considerable potential for variation (Stacy, 1967 a).
ROOM
PLAN, FURNITURE
AND EQUIPMENT
The room plans for this surgical laboratory are set out broadly in Fig. I. Bench space and chair arrangements (Fig. 2) have been established in an air-conditioned environment so that a maximum of 20 students (working in pairs) can be accommodated at any one teaching session Each of the 10 bench locations is provided with the latest model of the pig’s head clamp (a Figs 2 and 3) to which can be attached either a prepared pig mandible or maxilla A set of 2 1 basic oral-surgical instruments (including four dental elevators) is provided in a lockable cabinet (b in Fig 3) at each bench position Surgical suction (c in Fig. 3) is also available to each position, as is a small cupsink with running water via a gooseneck tap (d in Fig 3). A liquid antiseptic surgical scrub facility with paper hand towelling is conveniently located. Wall cupboards with lockable sliding glass doors (i in Figs 1 and 2) provide ample space for oral-surgical teaching
Stacy: Oral-surgical
technique
319
teaching
2
/
ELEVATION
I
Fig. 1. Layout of an oral-surgical-technique teaching laboratory 1, Plan, scale l/l 00.2, Elevation, scale l/25. a. Door; b. deep freeze unit’ c, bench position; d, cupsmk; e, structural columns; f. storage cupboard; g, preparation area and sink; h. garbage disposal; i, display cabinets (one wall only); f, instrument cabinet and suction (under).
models and displays. A large cupboard (fin Fig I ), beside which is a large sink (g in Fig. 1) with a broad preparation area for the heads and space for a freestanding butcher’s band saw if desired, completes the basic requirements.
SPECIMEN
PREPARATION,
DISPOSAL
AND COST
There is need for special preparation and storage for the heads before teaching sessions, and these special needs are catered for conveniently within the technique laboratory. A stepbystep description of the preparation of a fresh pig’s head for the purpose of technique teaching was previously described (Stacy, 1967 a). The maxilla and mandible are first disarticulated and, when adequately prepared and wiped down with aqueous hibitane, they are stacked in layers between plastic sheeting and frozen fresh. The plastic sheets allow for ease when unpacking individual frozen jaw specimens. The jaws are thawed at room temperature for approximately eight hours before use. The thawing process can be delayed by transfer to a refrigerator for 24 hours before they are required.
320
Journal of Dentistry, Vol. 1 ~/NO. 4 (1985)
Fig. 2. Students laboratory.
working
at bench
F&. 3. Equipment position.
positions
available
at
in ora!-surgical-technique
each
bench
Labora tory teaching with pig’s heads remains economically viable in Australia in 1985. The heads are obtained fresh from the local abattoir. With the cost of a pig’s head presently at $ Al, a session for 20 students can be mounted for $A10 plus the cost of materials. At the conclusion of each session the waste is double-bagged and disposed of through the hospital c:ontaminated waste system by incineration.
Stacy: Oral-surgical
POTENTIAL
technique
321
teaching
FOR INFECTION
A recurrent but sensible question concerns the risk of serious infections arising from the use of animal material in this manner, There has of course been the occasional minor accident-a superficial scratch or minor skin laceration-and one must be concerned with the possibility of consequent infection in such a circumstance. It can be stated that in23 year’s experience ofthis teaching method using pigs’ heads, more than 1200 students have passed through these courses and there have been no related infections or serious injury in that time. It is unequivocal that, in our experience, the dangers of infections are minimal and must be far less than the dangers in this regard presenting daily to meat vendors. Nonetheless, it is only sensible to observe simple precautions. For example, the heads are carefully cleaned down’with aqueous hibitane before use and students are encouraged to wear gloves and aprons while operating on the animal heads (Fig. 2). Students are instructed in the correct handling of a scalpel and sharp instruments and this includes an emphasis on the need for adequate support to prevent uncontrolled movements which could lead to laceration of either the patient or the operator.
ISOLATION
OF ORGANISMS
In a study which endeavoured to show the incidence of likely pathogenic organisms present in the specimens of pig stock available for our use, it was not possible to isolate spirochaetes, yeasts or mycelium. In anaerobic culture Clostridium tetani could not be grown. In some countries the presence of Trichinella spiralis might well be a problem, but as the larvae will not survive freezing (24 hours at -32 “C or -15 “C for three weeks) (Wyngaarden and Smith, 1982) it would be advisable to follow our own routine of preparation of the heads followed by deepfrozen storage until required QFever, caused by a rickettsial agent ( Coxiella burnettii), is a recognized animal-laboratory hazard but is associated with calves and sheep, mice, hamsters and guinea-pigs and rarely, if ever, affects pigs. Erysipelas is known to involve pigs, and group A streptococci have been isolated in small numbers in these specimens (see bacteriological analysis). Local veterinary advice would confirm our own experience that there is no evidence that erysipelas is a hazard of any concern with these animal-laboratory sessions. Organisms isolated from the pig oral cavity were: Gram +ve cocci, Gram -ve cocci, Gram +ve rods and Gram -ve rods (No pus cells, spirochaetes, yeasts or mycelium were seen). Results of quantitative analysis of bacteriological smears are shown in Table Z.
GRADUATE
MICROSURGICAL
WORKSHOP
This special-purpose laboratory is also used in graduate education. There are many graduate surgical exercises which do benefit from initial explanation and practice on animal heads. New procedures can be devised and attempted before being tried out in the clinical situation. It is well recognized that the detailed practice of microsurgical techniques in an experimental laboratory situation is an essential step in the preparation of a surgeon and his assistant for such tine work on patients. With microsurgical work, the basic manipulations should be practised in such a laboratory before a patient is subjected to a procedure, the success of which depends upon the precision of the surgeon (O’Brien, 1976; Austin et al., 1983).
322
Journal of Dentistry,
Table /1 Quantitative
analysis of bacteriological Buccal sulcus Before After hibitane hibitane
Gram Gram Gram Gram
+ve +ve -ve -ve
cocci rods cocci rods
+ + + +
+ nil nil nil
Vol. 1 ~/NO. 4 (1985)
smears Lingual sulcus Before After hibitane hibitane + nil nil +
nil nil nil nil
+++, Profuse growth; ++. moderate growth; +, scanty growth; nil, no organisms seen. The following organisms were identified: alpha haemolytic streptococci; beta haemolytic streptococci (non group A); Staphylococcus a/bus unidentified Gram -ve bacilli (other than Bacillus spp.): Neisseraceae; Bacillus spp.; coliform bacilli: non-haemolytic diplococci; motile aerobic Gram -ve Bacillus (?pfoteus).
An operating microscope together with basic microsurgical instruments has been made available for graduate tuition in this oral-surgery technique laboratory and a high degree of manual dexterity can be achieved in this demanding field before commencing clinical work with patients. REFERENCES
Austin G. T., Hammond F. W., Schaberg S. J. et al. (1983) A laboratory model for vascular microsurgery. J. Oral Maxillofac. Surg. 41, 450. Bonnette G. H. and Hayward J. R (1969) Introductory approach to the study of oral surgery: preclinical laboratory. J. Dent Educ. 33, 350. Moore J. R, Stacy G. C. and Gillbe G. V. (1965) The use of models and animal heads in the teaching of oral surgery techniques. Dent. Pratt. Dent Rec. 15, 337. O’Brien B. McC. (1976) Replantation and reconstructive microvascular surgery. Ann. R Coil. Surg. Eng. 58, 87.
Stacy G. C. (1966) A combined clamp and tray for the management of the pig’s head in the teaching of oral surgery techniques. Dent. Pratt Dent. Rec. 16,259. Stacy G. C. (1967a) The pig’s head as a teaching device in oral surgery. Aust Dent. J. 12, 160.
Stacy G. C. (1967 b) A further useful clamp for the management of the pig’s head in teaching oral surgery techniques. Dent. Pratt. Dent. Rec. 17, 355. Wyngaarden J. B. and Smith L. H. (eds) (1982) Cecil Textbook of Medicine. Philadelphia, Saunders, p. 1772.
A laboratory technique G. C. Stacy, Depa/tment Westmead
for teaching
BDS, FDSRCS, DOrth KS, of Oral Medicine
Dental
Primed in Greaf Britain
and
oral-surgical
FRACDS
Oral Surgery
Clinical School, Westmead
The University
of Sydney
and
Hospital, NSW
ABSTRACT A special-purpose laboratory designed to improve the efticiency of simulated teaching of oral-surgical techniques at both undergraduate and graduate levels is described The laboratory is recommended because it has simplified further the staging of oral-surgical-technique teaching The possible risk of infections from the use of animal tissue in this type of laboratory is also discussed.
INTRODUCTION Teaching oral-surgical technique on pig’s heads was originally undertaken with the prepared jaw sitting free in a metal tray (Moore et al., 1965). Subsequently, specially designed laboratory clamps were developed (Stacy, 1966, 1967 b) which allowed for greater safety and ease of management of the specimens during teaching sessions in a prosthetic laboratory. A self-contained laboratory entirely devoted to animal head (pig) and other practical demonstrations before oral-surgical clinical work was foreshadowed in 1966 as a highly efftcient workshop for undergraduate and graduate university education (Stacy, 1966). This complete concept has now been incorporated into the new teaching facility for the Faculty of Dentistry, University of Sydney within the Department of Oral and Maxillo-Facial Surgery, Westmead Dental Clinical School, Westmead, NSW and is proving to be a powerful addition to the oral-surgical teaching programme. The value of having simulated oral-surgical exercises presented in an orderly sequence in a suitably equipped laboratory has also been recognized by others (Bonnette and Hayward, 1969). The content of each teaching session is tailored to the student requirements but there is considerable potential for variation (Stacy, 1967 a).
ROOM
PLAN, FURNITURE
AND EQUIPMENT
The room plans for this surgical laboratory are set out broadly in Fig. I. Bench space and chair arrangements (Fig. 2) have been established in an air-conditioned environment so that a maximum of 20 students (working in pairs) can be accommodated at any one teaching session Each of the 10 bench locations is provided with the latest model of the pig’s head clamp (a Figs 2 and 3) to which can be attached either a prepared pig mandible or maxilla A set of 2 1 basic oral-surgical instruments (including four dental elevators) is provided in a lockable cabinet (b in Fig 3) at each bench position Surgical suction (c in Fig. 3) is also available to each position, as is a small cupsink with running water via a gooseneck tap (d in Fig 3). A liquid antiseptic surgical scrub facility with paper hand towelling is conveniently located. Wall cupboards with lockable sliding glass doors (i in Figs 1 and 2) provide ample space for oral-surgical teaching
Stacy: Oral-surgical
technique
319
teaching
2
/
ELEVATION
I
Fig. 1. Layout of an oral-surgical-technique teaching laboratory 1, Plan, scale l/l 00.2, Elevation, scale l/25. a. Door; b. deep freeze unit’ c, bench position; d, cupsmk; e, structural columns; f. storage cupboard; g, preparation area and sink; h. garbage disposal; i, display cabinets (one wall only); f, instrument cabinet and suction (under).
models and displays. A large cupboard (fin Fig I ), beside which is a large sink (g in Fig. 1) with a broad preparation area for the heads and space for a freestanding butcher’s band saw if desired, completes the basic requirements.
SPECIMEN
PREPARATION,
DISPOSAL
AND COST
There is need for special preparation and storage for the heads before teaching sessions, and these special needs are catered for conveniently within the technique laboratory. A stepbystep description of the preparation of a fresh pig’s head for the purpose of technique teaching was previously described (Stacy, 1967 a). The maxilla and mandible are first disarticulated and, when adequately prepared and wiped down with aqueous hibitane, they are stacked in layers between plastic sheeting and frozen fresh. The plastic sheets allow for ease when unpacking individual frozen jaw specimens. The jaws are thawed at room temperature for approximately eight hours before use. The thawing process can be delayed by transfer to a refrigerator for 24 hours before they are required.
320
Journal of Dentistry, Vol. 1 ~/NO. 4 (1985)
Fig. 2. Students laboratory.
working
at bench
F&. 3. Equipment position.
positions
available
at
in ora!-surgical-technique
each
bench
Labora tory teaching with pig’s heads remains economically viable in Australia in 1985. The heads are obtained fresh from the local abattoir. With the cost of a pig’s head presently at $ Al, a session for 20 students can be mounted for $A10 plus the cost of materials. At the conclusion of each session the waste is double-bagged and disposed of through the hospital c:ontaminated waste system by incineration.
Stacy: Oral-surgical
POTENTIAL
technique
321
teaching
FOR INFECTION
A recurrent but sensible question concerns the risk of serious infections arising from the use of animal material in this manner, There has of course been the occasional minor accident-a superficial scratch or minor skin laceration-and one must be concerned with the possibility of consequent infection in such a circumstance. It can be stated that in23 year’s experience ofthis teaching method using pigs’ heads, more than 1200 students have passed through these courses and there have been no related infections or serious injury in that time. It is unequivocal that, in our experience, the dangers of infections are minimal and must be far less than the dangers in this regard presenting daily to meat vendors. Nonetheless, it is only sensible to observe simple precautions. For example, the heads are carefully cleaned down’with aqueous hibitane before use and students are encouraged to wear gloves and aprons while operating on the animal heads (Fig. 2). Students are instructed in the correct handling of a scalpel and sharp instruments and this includes an emphasis on the need for adequate support to prevent uncontrolled movements which could lead to laceration of either the patient or the operator.
ISOLATION
OF ORGANISMS
In a study which endeavoured to show the incidence of likely pathogenic organisms present in the specimens of pig stock available for our use, it was not possible to isolate spirochaetes, yeasts or mycelium. In anaerobic culture Clostridium tetani could not be grown. In some countries the presence of Trichinella spiralis might well be a problem, but as the larvae will not survive freezing (24 hours at -32 “C or -15 “C for three weeks) (Wyngaarden and Smith, 1982) it would be advisable to follow our own routine of preparation of the heads followed by deepfrozen storage until required QFever, caused by a rickettsial agent ( Coxiella burnettii), is a recognized animal-laboratory hazard but is associated with calves and sheep, mice, hamsters and guinea-pigs and rarely, if ever, affects pigs. Erysipelas is known to involve pigs, and group A streptococci have been isolated in small numbers in these specimens (see bacteriological analysis). Local veterinary advice would confirm our own experience that there is no evidence that erysipelas is a hazard of any concern with these animal-laboratory sessions. Organisms isolated from the pig oral cavity were: Gram +ve cocci, Gram -ve cocci, Gram +ve rods and Gram -ve rods (No pus cells, spirochaetes, yeasts or mycelium were seen). Results of quantitative analysis of bacteriological smears are shown in Table Z.
GRADUATE
MICROSURGICAL
WORKSHOP
This special-purpose laboratory is also used in graduate education. There are many graduate surgical exercises which do benefit from initial explanation and practice on animal heads. New procedures can be devised and attempted before being tried out in the clinical situation. It is well recognized that the detailed practice of microsurgical techniques in an experimental laboratory situation is an essential step in the preparation of a surgeon and his assistant for such tine work on patients. With microsurgical work, the basic manipulations should be practised in such a laboratory before a patient is subjected to a procedure, the success of which depends upon the precision of the surgeon (O’Brien, 1976; Austin et al., 1983).
322
Journal of Dentistry,
Table /1 Quantitative
analysis of bacteriological Buccal sulcus Before After hibitane hibitane
Gram Gram Gram Gram
+ve +ve -ve -ve
cocci rods cocci rods
+ + + +
+ nil nil nil
Vol. 1 ~/NO. 4 (1985)
smears Lingual sulcus Before After hibitane hibitane + nil nil +
nil nil nil nil
+++, Profuse growth; ++. moderate growth; +, scanty growth; nil, no organisms seen. The following organisms were identified: alpha haemolytic streptococci; beta haemolytic streptococci (non group A); Staphylococcus a/bus unidentified Gram -ve bacilli (other than Bacillus spp.): Neisseraceae; Bacillus spp.; coliform bacilli: non-haemolytic diplococci; motile aerobic Gram -ve Bacillus (?pfoteus).
An operating microscope together with basic microsurgical instruments has been made available for graduate tuition in this oral-surgery technique laboratory and a high degree of manual dexterity can be achieved in this demanding field before commencing clinical work with patients. REFERENCES
Austin G. T., Hammond F. W., Schaberg S. J. et al. (1983) A laboratory model for vascular microsurgery. J. Oral Maxillofac. Surg. 41, 450. Bonnette G. H. and Hayward J. R (1969) Introductory approach to the study of oral surgery: preclinical laboratory. J. Dent Educ. 33, 350. Moore J. R, Stacy G. C. and Gillbe G. V. (1965) The use of models and animal heads in the teaching of oral surgery techniques. Dent. Pratt. Dent Rec. 15, 337. O’Brien B. McC. (1976) Replantation and reconstructive microvascular surgery. Ann. R Coil. Surg. Eng. 58, 87.
Stacy G. C. (1966) A combined clamp and tray for the management of the pig’s head in the teaching of oral surgery techniques. Dent. Pratt Dent. Rec. 16,259. Stacy G. C. (1967a) The pig’s head as a teaching device in oral surgery. Aust Dent. J. 12, 160.
Stacy G. C. (1967 b) A further useful clamp for the management of the pig’s head in teaching oral surgery techniques. Dent. Pratt. Dent. Rec. 17, 355. Wyngaarden J. B. and Smith L. H. (eds) (1982) Cecil Textbook of Medicine. Philadelphia, Saunders, p. 1772.