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Management of root perforations: Classification, diagnosis, prevention, and treatment
tics what the intraoral camera has done for general dentistry. Abstracted by Bruce R. Hilt, DDS, Postgraduate Endodontics, University of Florida College of Dentistry, Gainesville, Florida.
Scientific Session Vl Principles of Modern Endodontic Surgery Mahmoud Torabinejad, DMD, MSD, PhD (Loma Linda, CA) This session presented a review of modern endodontic surgery with the following objectives: 1) to describe how periradicular lesions develop; 2) to identify the indications for periradicularand correctivesurgeries; 3) to describe the advantages and disadvantages of bur and ultrasonic root-end preparations; 4) to enumerate the advantages and disadvantages of various root-end filling materials; and 5) to describe histologic healing following endodontic surgery. After a brief review of the pathogenesis of periapical lesions, Dr. Torabinejad highlighted the fact that most root canals that fail do so as a result of inadequate cleaning, shaping, and/or obturation of the root canal system. Every attempt should be made to retreat these teeth nonsurgically before surgery is considered. Even if nonsurgical retreatment is not 100% successful, the local environment of the canal has been improved, which is a determinant of surgical success. Indications for surgery include symptomatic cases, calcified canals, irretrievable filling material, presence of a non-removable post, unusual anatomic variation, horizontal apical fractures, procedural accidents (separated instrument, non-negotiableledge, over-extended filling), and exploratorysurgery. Dr. Torabinejadpresentedan extensive slide show documenting many of the situations previously mentioned, including treatment of an antral perforation and a palatal approach to periradicularsurgery. Many factors affect the seal of a resected root end including the level of resection, the angle of resection, the cross-sectional size of the resected table, and the size of the dentinal-restoration junction. Root-end preparations should simulate original canal anatomy, be parallel with the long axis of the root, be prepared within the confines of the root canal, and be of adequate width and depth. Dr. Torabinejad quoted a study by Gorman et al. (J Endod, 1995) that found that ultrasonic root-end preparations were smaller and more parallel than bur root-end preparations but exhibited more fractures in the resected root-end. His recommendations for the use of ultrasonic root-end preparations included avoiding thin walls, using low power settings, and a light touch. The session concluded with a discussion of various root-end filling materials and their respective advantages and disadvantages. The most recent filling material is mineral trioxide aggregate (MTA), a substance that is hydrophilic, provides a tighter seal than amalgam or Super EBA, is biocompatible,can regeneratetissue (bone, cementum), and has a long setting time and low compressive strength. Long-term studies of this material have yet to be carried out. Abstracted by Timothy J. McManus, DDS, Graduate Endodontics, University of Detroit Mercy School of Dentistry, Detroit, MI.
Scientific Session VII Management of Root Perforations: Classification, Diagnosis, Prevention, and Treatment Zvi Fuss, DMD (Tel Aviv, Israel) Root perforations are defined as artificial or pathologic openings along the root surface that connect the root canal space with surrounding tissues or the oral cavity. Post perforations account for 53% of these, while 47% are endodontically related. Of the endodontic perforations, 42% occur during negotiation of calcified canals, 35% occur during instrumentation, and 23% occur locating calcified canals. The prognosis for a perforation is dependent on several factors: the time between perforation and treatment, the size of the perforation, and the location of the perforation. Dr. Fuss presented a system of classification of perforations based on these factors. He feels the most important factor is the relationship of the perforation to the bone level. The critical zone is the crestal bone and the epithelial attachment area. Perforations apical to the crestal bone have a generally good prognosis if the main canal can be cleaned and the extra opening
sealed. Even mid-root perforations have a good prognosis if there are no pockets or communications with the epithelial attachment. Furcation perforations generally have a poor prognosis if the perforation occurs near the crestal bone. To summarize, the prognosis is good when the perforation is fresh, small, apical to the crestal bone and epithelial attachment, and on the lateral root surface. The prognosis is poor when the perforation is old, large, at the crestal level, and/or in the furcation. The electronic apex Iocator was shown to locate accurately and confirm the presence of a perforation in most cases studied. Prevention is the best treatment for perforations, and emphasis was placed on removing old filling materials or crowns, making a large access opening whenever calcified canals are being searched for, and using proper instruments and instrumentation techniques. The treatment of a fresh apical perforation in routine endodontics is to seal the perforation as if it were an extra canal opening. Calcium hydroxide is recommendedfor old apical perforations to form a calcific barrier. However, calcium hydroxide is ineffective in treating furcation perforations. Better results were shown using Sealapex (pH 7-8) than pure calcium hydroxide (pH 12.5). For sealing lateral perforations, silver-glass ionomer cement was recommended without the use of an external matrix. The glass ionomer is mixed to a creamy consistency and painted over the defect working in from the periphery. The endodontics is then completed, and the initial internal glass ionomer acts as a matrix for a thicker mix of ionomer used to fill the chamber. This technique is designed to prevent any material from entering the bone or periodontium. Dr. Fuss emphasized the need not to place any materials external to the perforation, intentionally or unintentionally. Abstracted by Arnold H. Gartner, DDS, Assistant Professor, University of Detroit Mercy School of Dentistry, Detroit, MI.
Scientific Session VIII Recent Advances in Retreatment Gary B. Carr, DDS (San Diego, CA) The AAE glossary of endodontic terminology defines retreatment as a procedure to remove root canal filling materialsfrom the tooth and again clean, shape, and obturate the canals. Dr. Carr believes this definition is disadvantageous to endodontists and proposed the following: retreatment is a procedure performed on a tooth that has had prior attempted definitive treatment that has produced a result requiring additional treatment to ensure a successful result. Endodontic practices must be designed to handle mismanaged cases. The problems with retreatment perceived by most endodontists are: 1) frustration due to difficult cases, 2) frequent displeasure with the clinical results, and 3) high cost. Using an extensive series of cases, Dr. Carr illustrated what is possible in nonsurgical retreatment using the surgical operating microscope. "All microscopes will do what you want them to do. It is not the equipment, its the doctor that makes the difference." He emphasized that the doctor and assistant need to be well-trained in the use of the microscope and that the operatory needs to be organized with everything at your fingertips. There is no aspect of endodontics which is not done better and more competently using a microscope. There is a learning curve, but after one develops skill it is easier, better, and faster with the microscope than without it. Several techniques to disassemble previous restorative dentistry (crowns, bridges, and posts) were discussed, as were methods to remove obstructions (silver points, resin cements, and fragmented instruments) easily from the coronal mid-root and apical third of canals. Dr. Carr described various instruments, materials, and methods to locate and instrument calcified or missed canals. He advocated placing a drop of bleach into the access opening as an aid to locate canals and also to determine when canals are ready to obturate. When bleach contacts pulpal tissue, bubbles, which can be seen through the microscope, are released. The session concluded with a discussion of the various methods of repairing perforations using an internal approach. Abstracted by H. Robert Steiman, PhD, DDS, MSD, Program Director, University of Detroit Mercy School of Dentistry, Detroit, MI.
Scientific Session Vl Principles of Modern Endodontic Surgery Mahmoud Torabinejad, DMD, MSD, PhD (Loma Linda, CA) This session presented a review of modern endodontic surgery with the following objectives: 1) to describe how periradicular lesions develop; 2) to identify the indications for periradicularand correctivesurgeries; 3) to describe the advantages and disadvantages of bur and ultrasonic root-end preparations; 4) to enumerate the advantages and disadvantages of various root-end filling materials; and 5) to describe histologic healing following endodontic surgery. After a brief review of the pathogenesis of periapical lesions, Dr. Torabinejad highlighted the fact that most root canals that fail do so as a result of inadequate cleaning, shaping, and/or obturation of the root canal system. Every attempt should be made to retreat these teeth nonsurgically before surgery is considered. Even if nonsurgical retreatment is not 100% successful, the local environment of the canal has been improved, which is a determinant of surgical success. Indications for surgery include symptomatic cases, calcified canals, irretrievable filling material, presence of a non-removable post, unusual anatomic variation, horizontal apical fractures, procedural accidents (separated instrument, non-negotiableledge, over-extended filling), and exploratorysurgery. Dr. Torabinejadpresentedan extensive slide show documenting many of the situations previously mentioned, including treatment of an antral perforation and a palatal approach to periradicularsurgery. Many factors affect the seal of a resected root end including the level of resection, the angle of resection, the cross-sectional size of the resected table, and the size of the dentinal-restoration junction. Root-end preparations should simulate original canal anatomy, be parallel with the long axis of the root, be prepared within the confines of the root canal, and be of adequate width and depth. Dr. Torabinejad quoted a study by Gorman et al. (J Endod, 1995) that found that ultrasonic root-end preparations were smaller and more parallel than bur root-end preparations but exhibited more fractures in the resected root-end. His recommendations for the use of ultrasonic root-end preparations included avoiding thin walls, using low power settings, and a light touch. The session concluded with a discussion of various root-end filling materials and their respective advantages and disadvantages. The most recent filling material is mineral trioxide aggregate (MTA), a substance that is hydrophilic, provides a tighter seal than amalgam or Super EBA, is biocompatible,can regeneratetissue (bone, cementum), and has a long setting time and low compressive strength. Long-term studies of this material have yet to be carried out. Abstracted by Timothy J. McManus, DDS, Graduate Endodontics, University of Detroit Mercy School of Dentistry, Detroit, MI.
Scientific Session VII Management of Root Perforations: Classification, Diagnosis, Prevention, and Treatment Zvi Fuss, DMD (Tel Aviv, Israel) Root perforations are defined as artificial or pathologic openings along the root surface that connect the root canal space with surrounding tissues or the oral cavity. Post perforations account for 53% of these, while 47% are endodontically related. Of the endodontic perforations, 42% occur during negotiation of calcified canals, 35% occur during instrumentation, and 23% occur locating calcified canals. The prognosis for a perforation is dependent on several factors: the time between perforation and treatment, the size of the perforation, and the location of the perforation. Dr. Fuss presented a system of classification of perforations based on these factors. He feels the most important factor is the relationship of the perforation to the bone level. The critical zone is the crestal bone and the epithelial attachment area. Perforations apical to the crestal bone have a generally good prognosis if the main canal can be cleaned and the extra opening
sealed. Even mid-root perforations have a good prognosis if there are no pockets or communications with the epithelial attachment. Furcation perforations generally have a poor prognosis if the perforation occurs near the crestal bone. To summarize, the prognosis is good when the perforation is fresh, small, apical to the crestal bone and epithelial attachment, and on the lateral root surface. The prognosis is poor when the perforation is old, large, at the crestal level, and/or in the furcation. The electronic apex Iocator was shown to locate accurately and confirm the presence of a perforation in most cases studied. Prevention is the best treatment for perforations, and emphasis was placed on removing old filling materials or crowns, making a large access opening whenever calcified canals are being searched for, and using proper instruments and instrumentation techniques. The treatment of a fresh apical perforation in routine endodontics is to seal the perforation as if it were an extra canal opening. Calcium hydroxide is recommendedfor old apical perforations to form a calcific barrier. However, calcium hydroxide is ineffective in treating furcation perforations. Better results were shown using Sealapex (pH 7-8) than pure calcium hydroxide (pH 12.5). For sealing lateral perforations, silver-glass ionomer cement was recommended without the use of an external matrix. The glass ionomer is mixed to a creamy consistency and painted over the defect working in from the periphery. The endodontics is then completed, and the initial internal glass ionomer acts as a matrix for a thicker mix of ionomer used to fill the chamber. This technique is designed to prevent any material from entering the bone or periodontium. Dr. Fuss emphasized the need not to place any materials external to the perforation, intentionally or unintentionally. Abstracted by Arnold H. Gartner, DDS, Assistant Professor, University of Detroit Mercy School of Dentistry, Detroit, MI.
Scientific Session VIII Recent Advances in Retreatment Gary B. Carr, DDS (San Diego, CA) The AAE glossary of endodontic terminology defines retreatment as a procedure to remove root canal filling materialsfrom the tooth and again clean, shape, and obturate the canals. Dr. Carr believes this definition is disadvantageous to endodontists and proposed the following: retreatment is a procedure performed on a tooth that has had prior attempted definitive treatment that has produced a result requiring additional treatment to ensure a successful result. Endodontic practices must be designed to handle mismanaged cases. The problems with retreatment perceived by most endodontists are: 1) frustration due to difficult cases, 2) frequent displeasure with the clinical results, and 3) high cost. Using an extensive series of cases, Dr. Carr illustrated what is possible in nonsurgical retreatment using the surgical operating microscope. "All microscopes will do what you want them to do. It is not the equipment, its the doctor that makes the difference." He emphasized that the doctor and assistant need to be well-trained in the use of the microscope and that the operatory needs to be organized with everything at your fingertips. There is no aspect of endodontics which is not done better and more competently using a microscope. There is a learning curve, but after one develops skill it is easier, better, and faster with the microscope than without it. Several techniques to disassemble previous restorative dentistry (crowns, bridges, and posts) were discussed, as were methods to remove obstructions (silver points, resin cements, and fragmented instruments) easily from the coronal mid-root and apical third of canals. Dr. Carr described various instruments, materials, and methods to locate and instrument calcified or missed canals. He advocated placing a drop of bleach into the access opening as an aid to locate canals and also to determine when canals are ready to obturate. When bleach contacts pulpal tissue, bubbles, which can be seen through the microscope, are released. The session concluded with a discussion of the various methods of repairing perforations using an internal approach. Abstracted by H. Robert Steiman, PhD, DDS, MSD, Program Director, University of Detroit Mercy School of Dentistry, Detroit, MI.