0099-2399/91/1711-0570/$03.00/0 JOURNAL OF ENDODONTICS Copyright 9 1991 by The American Association of Endodontists
Printed in U.S.A.
VOL. 17, NO. 11, NOVEMBER1991
CLINICAL AID The Radiographic Platform: A New Method to Evaluate Root Canal Preparation In Vitro Gilson Blitzkow Sydney, DDS, Antonio Batista, DDS, and Luciano Loureiro de Melo, DDS
An in vitro method for evaluating root canal preparation in curved canals is presented. Based on Schneider's method, this technique makes it possible to obtain the position of the instrument before and after instrumentation in the same X-ray film. The use of the radiographic platform is a valuable research and teaching aid.
the deviation from the original position resulting from the Roane technique of instrumentation. The radiographic platform is an apparatus that enables one to visualize the position of the instrument before and after root canal preparation on the same X-ray film. In this way any inadequate instrument usage can be evaluated. T H E R A D I O G R A P H I C P L A T F O R M APPARATUS The radiographic platform is very easy to make. The necessary materials are (a) a clamp, (b) a plastic ice cube mold (only one piece), (c) two lids of gutta-percha boxes (Kerr), (d) a plastic ruler, and (e) an adhesive cement. First, a rectangular ice cube mold is cut and one piece detached. One of the gutta-percha lids is cut 3 m m from one of its sides according to Fig. 1. Using a carborundum disc the ruler is cut longer than the clamp diameter which must be adjusted to the X-ray tube. The ruler is cemented to the clamp as shown in Fig. 2. The second gutta-percha lid is used as a base for the ice mold. The ice cube mold piece must be cemented to the ruler, the base, and the gutta-percha lid piece as seen in Fig. 3. Once the radiographic platform is assembled
Root canal preparation has been considered the most important phase in endodontic therapy. The objectives of root canal preparation can be defined as cleaning and shaping. This includes a complete debridment of all areas, leaving the foramen in its original position, keeping the foramen at a suitable diameter, and developing a continuously tapering conical form (1-3). When these objectives are properly met an efficient obturation of the root canal system is possible. Preparation is easily accomplished in straight canals, but when root canal curvatures are present it becomes more difficult. In narrow, curved canals the apical area is difficult to clean and shape, and there is a tendency for ledging and zipping (4). To reduce these possibilities various flaring techniques have been devised. Evaluation of the efficiency of root canal instrumentation has been analyzed by means of the c o m m o n optical microscope, the scanning electron microscope, radiographic examination, photographic studies, root canal models, and, recently, the computer (5). A problem in root canal evaluation is that the anatomical morphology and curvatures are often subject to examination only after instrumentation. Bramante et al. (5) developed a method that permits an analysis before, during, and after root canal preparation using teeth in acrylic resin blocks sectioned transversally. Schneider, in 1981 (6), introduced a method using a projector to increase the size of the tooth by 10 times. First, a line was scribed on the radiograph parallel to the tooth's long axis. A second line was then drawn from the apical foramen to intersect with the first at the point where the canal began to leave the long axis of the tooth. The acute angle formed was used by many authors to evaluate root canal preparation. With the use of this technique, Southard et at. (7) analyzed
FIG 1. The necessary materials: a, the clamp; b, a plastic ice cube mold; c, gutta-percha box lids; and d, plastic ruler.
570
Vol. 17, No. 11, November 1991
FIG 2. The ruler is cemented to the clamp and the ice cube mold to the lid of a gutta-percha box.
The Radiographic Platform
571
FIG 5. Connected to the X-ray tube.
METHODOLOGY
FIG 3. The radiographic platform assembled.
F~G4. Painted black with the acrylic resin block in place.
it may be painted any color and connected to the X-ray equipment by the clamp which has been previously adjusted to the proper diameter (Figs. 4 and 5).
The tooth with a curved root canal selected to be studied is immersed in clear autocured acrylic resin using another plastic ice cube piece of the same size, making a block, so that the crown will stick out. There are several techniques to hold the tooth in the correct position until it is completely fixed in the resin. One of the techniques is to attach it to the middle of a toothpick with wax. The two ends of the toothpick will rest on the edges of the ice cube mold. After access, a file is introduced into the root canal in order to determine the correct working length. The resin block with the tooth is placed in the radiographic platform and an X-ray film is exposed and developed. Once the proper working length is determined, another X-ray film is exposed but left in the radiographic platform. It is not developed now and it will be used later to overlap images. The resin block must be taken out of the apparatus and the canal prepared according to the technique to be tested. When it is fully instrumented, the resin block is placed in the radiographic platform again. The last file used is kept inside of the canal and a new exposure is made on the second X-ray film. The most important point to be carefully observed to assure accuracy when superimposing the last image over the first on the second X-ray film is that after the first exposure the film has to be kept steady in the platform. There is no problem with the X-ray beam because it is guided by the clamp. The exposure time used for both incidences is 5/1os. The developing time must be shortened in order to prevent darkening of the film. These factors have to be adjusted according to the characteristics of the X-ray film and the X-ray machine used. After developing the X-ray film it can be framed for a slide projector so that it will be easier to detect ledging or zipping and to check if the instrumentation damaged the thickness of the mesio-distal walls of the root canal. The original position of the instrument as well as the postinstrumentation portion will be seen in the same film (Figs. 6 and 7).
572
Sydney et al.
Journal ofEndodonfics
FIG 6. The overlapping image of the t w o files indicates desirable instrument usage.
detect the presence of ledging and zipping and to analyze the action of the instrument on the thickness of the mesio-distal walls of the root canal. Similar devices were used before by Southard et al. (7) in 1987, by Bastos Filho (8) in 1989, and recently by Moraes et al. (9). The idea was to obtain the same angularity in order to use Schneider's method. Schneider (6) used two X-ray films to determine the degree of canal curvature before and after root canal preparation. The proposed method makes it possible to have the position of the file at the beginning and at the end of instrumentation in the same film. Deviations and imperfections as ledging and zipping are directly observed. If the canal is correctly prepared, the two files must be overlapped in the apical third (Fig. 6). If not, since deviation is clearly seen, an angle will be detected. It is advisable to eliminate other roots when working on upper molars in order to avoid image overlapping (Fig. 7). The use of the radiographic platform can prove to be a useful teaching aid and it may be valuable for endodontic research. Dr. Sydney is adjunct professor, Department of Endodontics, Dr. Batista is a volunteer clinical instructor, Department of Endodontics, and Dr. de Melo is chairman, Department of Endodontics, School of Dentistry, Federal University of Parana, Parana, Brazil. Address requests for reprints to Dr. GUson B. Sydney, Lua Benjamin Constant 145, 1 Andar, S-2 CEP-80060, Curitiba, Parana, Brazil.
References
F~G 7. The files d o not superimpose at the a p e x due to incorrect use of the instrument.
DISCUSSION Many methods have been described to evaluate the root canal preparation. The use of the radiographic platform is a practical and informative one because it makes it easy to
1. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974; 18: 269-96. 2. Abou-Rass M. Endodontic preparation and filling procedures. Los Angeles: West Coast Arts, The California Dental Institute for Continuing Education, 1986. 3. Calhoun G, Montgomery S. The effects of four instrumentation techniques on root canal shape. J Endodon 1988;14:273-7. 4. Abou-Rass M, Frank A, Glick DH. The anticurvature filing method to prepare the curved root canal. Am Dent Assoc 1980;101:792-4. 5. Bramante CM, Berbet A, Borges RP. A methodology for evaluation of root canal instrumentation. J Endodon 1987;13:243-5. 6. Schneider SW. Comparison of root canal preparation in straight and curved canals. J Oral Surg 1971 ;32:271-5. 7. Southard DW, Oswald RJ, Natkin E. Instrumentation of curved molar root canal with the Roane technique. J Endodon 1987;13:479-89. 8. Bastos Filho E. Analise "in vitro" da vada~:~o angular e da configura~:~lo apical quando do preparo de canals curvos corn instrumentos de tipo e proced~ncia variados [Tese Mestrado]. S&o Paulo, Brazil: Faculdade de Odontologia da Universidade de S&o Paulo-Brasil, 1989, 57 p. 9. Moraes SH, Batista A, Arag&o EM, Heck AR. Deformacion apical con diferentes tipos de limas, di&metros y numeros de usos en canales curvos. Rev Esp Endod (in press).
Printed in U.S.A.
VOL. 17, NO. 11, NOVEMBER1991
CLINICAL AID The Radiographic Platform: A New Method to Evaluate Root Canal Preparation In Vitro Gilson Blitzkow Sydney, DDS, Antonio Batista, DDS, and Luciano Loureiro de Melo, DDS
An in vitro method for evaluating root canal preparation in curved canals is presented. Based on Schneider's method, this technique makes it possible to obtain the position of the instrument before and after instrumentation in the same X-ray film. The use of the radiographic platform is a valuable research and teaching aid.
the deviation from the original position resulting from the Roane technique of instrumentation. The radiographic platform is an apparatus that enables one to visualize the position of the instrument before and after root canal preparation on the same X-ray film. In this way any inadequate instrument usage can be evaluated. T H E R A D I O G R A P H I C P L A T F O R M APPARATUS The radiographic platform is very easy to make. The necessary materials are (a) a clamp, (b) a plastic ice cube mold (only one piece), (c) two lids of gutta-percha boxes (Kerr), (d) a plastic ruler, and (e) an adhesive cement. First, a rectangular ice cube mold is cut and one piece detached. One of the gutta-percha lids is cut 3 m m from one of its sides according to Fig. 1. Using a carborundum disc the ruler is cut longer than the clamp diameter which must be adjusted to the X-ray tube. The ruler is cemented to the clamp as shown in Fig. 2. The second gutta-percha lid is used as a base for the ice mold. The ice cube mold piece must be cemented to the ruler, the base, and the gutta-percha lid piece as seen in Fig. 3. Once the radiographic platform is assembled
Root canal preparation has been considered the most important phase in endodontic therapy. The objectives of root canal preparation can be defined as cleaning and shaping. This includes a complete debridment of all areas, leaving the foramen in its original position, keeping the foramen at a suitable diameter, and developing a continuously tapering conical form (1-3). When these objectives are properly met an efficient obturation of the root canal system is possible. Preparation is easily accomplished in straight canals, but when root canal curvatures are present it becomes more difficult. In narrow, curved canals the apical area is difficult to clean and shape, and there is a tendency for ledging and zipping (4). To reduce these possibilities various flaring techniques have been devised. Evaluation of the efficiency of root canal instrumentation has been analyzed by means of the c o m m o n optical microscope, the scanning electron microscope, radiographic examination, photographic studies, root canal models, and, recently, the computer (5). A problem in root canal evaluation is that the anatomical morphology and curvatures are often subject to examination only after instrumentation. Bramante et al. (5) developed a method that permits an analysis before, during, and after root canal preparation using teeth in acrylic resin blocks sectioned transversally. Schneider, in 1981 (6), introduced a method using a projector to increase the size of the tooth by 10 times. First, a line was scribed on the radiograph parallel to the tooth's long axis. A second line was then drawn from the apical foramen to intersect with the first at the point where the canal began to leave the long axis of the tooth. The acute angle formed was used by many authors to evaluate root canal preparation. With the use of this technique, Southard et at. (7) analyzed
FIG 1. The necessary materials: a, the clamp; b, a plastic ice cube mold; c, gutta-percha box lids; and d, plastic ruler.
570
Vol. 17, No. 11, November 1991
FIG 2. The ruler is cemented to the clamp and the ice cube mold to the lid of a gutta-percha box.
The Radiographic Platform
571
FIG 5. Connected to the X-ray tube.
METHODOLOGY
FIG 3. The radiographic platform assembled.
F~G4. Painted black with the acrylic resin block in place.
it may be painted any color and connected to the X-ray equipment by the clamp which has been previously adjusted to the proper diameter (Figs. 4 and 5).
The tooth with a curved root canal selected to be studied is immersed in clear autocured acrylic resin using another plastic ice cube piece of the same size, making a block, so that the crown will stick out. There are several techniques to hold the tooth in the correct position until it is completely fixed in the resin. One of the techniques is to attach it to the middle of a toothpick with wax. The two ends of the toothpick will rest on the edges of the ice cube mold. After access, a file is introduced into the root canal in order to determine the correct working length. The resin block with the tooth is placed in the radiographic platform and an X-ray film is exposed and developed. Once the proper working length is determined, another X-ray film is exposed but left in the radiographic platform. It is not developed now and it will be used later to overlap images. The resin block must be taken out of the apparatus and the canal prepared according to the technique to be tested. When it is fully instrumented, the resin block is placed in the radiographic platform again. The last file used is kept inside of the canal and a new exposure is made on the second X-ray film. The most important point to be carefully observed to assure accuracy when superimposing the last image over the first on the second X-ray film is that after the first exposure the film has to be kept steady in the platform. There is no problem with the X-ray beam because it is guided by the clamp. The exposure time used for both incidences is 5/1os. The developing time must be shortened in order to prevent darkening of the film. These factors have to be adjusted according to the characteristics of the X-ray film and the X-ray machine used. After developing the X-ray film it can be framed for a slide projector so that it will be easier to detect ledging or zipping and to check if the instrumentation damaged the thickness of the mesio-distal walls of the root canal. The original position of the instrument as well as the postinstrumentation portion will be seen in the same film (Figs. 6 and 7).
572
Sydney et al.
Journal ofEndodonfics
FIG 6. The overlapping image of the t w o files indicates desirable instrument usage.
detect the presence of ledging and zipping and to analyze the action of the instrument on the thickness of the mesio-distal walls of the root canal. Similar devices were used before by Southard et al. (7) in 1987, by Bastos Filho (8) in 1989, and recently by Moraes et al. (9). The idea was to obtain the same angularity in order to use Schneider's method. Schneider (6) used two X-ray films to determine the degree of canal curvature before and after root canal preparation. The proposed method makes it possible to have the position of the file at the beginning and at the end of instrumentation in the same film. Deviations and imperfections as ledging and zipping are directly observed. If the canal is correctly prepared, the two files must be overlapped in the apical third (Fig. 6). If not, since deviation is clearly seen, an angle will be detected. It is advisable to eliminate other roots when working on upper molars in order to avoid image overlapping (Fig. 7). The use of the radiographic platform can prove to be a useful teaching aid and it may be valuable for endodontic research. Dr. Sydney is adjunct professor, Department of Endodontics, Dr. Batista is a volunteer clinical instructor, Department of Endodontics, and Dr. de Melo is chairman, Department of Endodontics, School of Dentistry, Federal University of Parana, Parana, Brazil. Address requests for reprints to Dr. GUson B. Sydney, Lua Benjamin Constant 145, 1 Andar, S-2 CEP-80060, Curitiba, Parana, Brazil.
References
F~G 7. The files d o not superimpose at the a p e x due to incorrect use of the instrument.
DISCUSSION Many methods have been described to evaluate the root canal preparation. The use of the radiographic platform is a practical and informative one because it makes it easy to
1. Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974; 18: 269-96. 2. Abou-Rass M. Endodontic preparation and filling procedures. Los Angeles: West Coast Arts, The California Dental Institute for Continuing Education, 1986. 3. Calhoun G, Montgomery S. The effects of four instrumentation techniques on root canal shape. J Endodon 1988;14:273-7. 4. Abou-Rass M, Frank A, Glick DH. The anticurvature filing method to prepare the curved root canal. Am Dent Assoc 1980;101:792-4. 5. Bramante CM, Berbet A, Borges RP. A methodology for evaluation of root canal instrumentation. J Endodon 1987;13:243-5. 6. Schneider SW. Comparison of root canal preparation in straight and curved canals. J Oral Surg 1971 ;32:271-5. 7. Southard DW, Oswald RJ, Natkin E. Instrumentation of curved molar root canal with the Roane technique. J Endodon 1987;13:479-89. 8. Bastos Filho E. Analise "in vitro" da vada~:~o angular e da configura~:~lo apical quando do preparo de canals curvos corn instrumentos de tipo e proced~ncia variados [Tese Mestrado]. S&o Paulo, Brazil: Faculdade de Odontologia da Universidade de S&o Paulo-Brasil, 1989, 57 p. 9. Moraes SH, Batista A, Arag&o EM, Heck AR. Deformacion apical con diferentes tipos de limas, di&metros y numeros de usos en canales curvos. Rev Esp Endod (in press).
