- Email: [email protected]
Ultrasonic retrograde preparation
Oral Maxillofacial Surg Clin N Am 14 (2002) 167 – 172
Ultrasonic retrograde preparation Stuart E. Lieblich, DMD a,b,*, Bernard McGiverin, DDS, FICD, FACD c a
University of Connecticut Health Center, 236 Farmington Avenue, Farmington, CT 06030, USA, b Avon Oral and Maxillofacial Surgery, 34 Dale Road, Suite 105, Avon, CT 06001, USA c 95 West Entry, Staten Island, NY 10304, USA
The use of ultrasonic devices for apical preparation has dramatically improved the ease of apical surgery and most certainly has contributed to the increase in success rates now reported. Ultrasonic preparation permits a deep retrograde restoration to be placed, one of the key factors to a positive outcome. The ability of these devices to precisely follow the internal root canal anatomy also contributes to this success. Before the development of ultrasonic retropreparation tips, preparation of the apical region was obtained with a rotary instrument. The Hall highspeed turbine drill or a conventional dental handpiece using long-shank friction grip surgical burs were the instruments of choice. A Micro-contra-angle head (Union Broach, Brooklyn, NY) was developed for use on a low-speed straight handpiece. Originally, it was not autoclavable, and many clinicians reported constant gear jamming and difficulty with its use no matter how gently it was handled or lubricated. The use of rotary burs can create preparations that do not follow the long axis of the tooth and, therefore, have decreased apical sealing potential. Off-axis preparation may also sacrifice additional tooth structure and potentially predispose the tooth to root fracture.
Ultrasonic instruments Ultrasonic devices have been used in dentistry for many years for removal of calculus. Applying elec-
* Corresponding author: Avon Oral and Maxillofacial Surgery, 34 Dale Road, Suite 105, Avon, CT 06001. E-mail address: [email protected] (S.E. Lieblich).
trical voltage to piezoelectric ceramics or quartz produces ultrasonic mechanical vibration. The usual frequency is in the range of 30kHz, with a vibration amplitude of 300 mm. Cavitation effects are created with the use of water for an additional physical effect to displace debris and improve cutting efficiency while preventing significant heat formation. Devices are available from many companies (Fig. 1). Advantages of the ultrasonic preparation include the accessibility to the apex, permitting a smaller flap reflection, less bone removal, and less of an apical bevel. Fig. 2 shows the accessibility achieved with an ultrasonic tip at the apex of a tooth. The current piezoelectric, ultrasonic units using stainless steel or diamond-coated autoclavable retrotips allow preparations of the apex for retrofill from a nearly perpendicular approach. Mehlhaff et al compared 76 roots from 29 bilaterally matched pairs of human teeth in cadavers [1]. In the first group, ultrasonic preparations were made in the roots and then filled with amalgam alloy. In the second group, high-speed rotary bur preparations were made in the remaining 50% and filled with the same alloy. The teeth were then extracted and radiographed from both a mesio-distal and bucco-lingual aspect. The same operator performed all the procedures and none of the root-end preparations resulted in perforation. It was determined that the ultrasonic tip produces a deeper root-end preparation with minimum bevel of the root ends. Lin and colleagues studied teeth that were prepared with ultrasonic devices versus rotary instruments [2]. With the aid of image processing, they found the ultrasonic preparations to be more conservative, with less perforations, than those made with the rotary instruments. A study of bacterial leakage by
1042-3699/02/$ – see front matter D 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 9 9 ( 0 2 ) 0 0 0 1 9 - 5
168
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
Fig. 1. Examples of ultrasonic units for apical preparations. All units have autoclavable tips and adjustable power settings.
Chailertvanitkul found significantly more leakage with rotary preparations in comparison with ultrasonic devices [3]. In their study, both groups had the same root-end filling material (super-EBA). Many ultrasonic devices have both stainless steel – and diamond-coated tips for apical preparation. The use of diamond-coated tips permits faster preparation with more gentle pressure. This was verified by Peters, who found a statistically significant reduction in preparation time with the diamond tips in comparison with stainless steel [4]. The diamond tips do remove more dentin and, therefore, should be used carefully to prevent overpreparation. Dye penetration studies that reveal leakage to bacteria
did not show a difference between diamond-coated tips and stainless steel [5].
Flap design Strict adherence to the surgical principles of sharp elevation of a mucoperiosteal flap is essential because perforation of the periosteum can nearly always guarantee hemorrhagic ooze throughout the operation and wound dehiscence afterward. Once the flap is elevated sufficiently, a broad-based retractor such as a Minnesota or Seldin retractor can be used. The McGivern Retractor (W. Lorenz, Jacksonville, FL) is also of
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
Fig. 2. Example of ultrasonic tip for preparation of root apex.
value here because it combines the broad-based end of the Seldin 23 elevator with an ergonomic handle. Care must be taken to keep all retractors firmly situated on the bone to prevent periosteal tearing. Worse yet, impingement on the flap fold can result in ischemia and slough and cause a severe periodontal problem. Surgical technique The high-speed surgical bur (2 mm or #8 round) is used to remove enough cortical bone to expose the apical region. The root apex should not be resected until the full apical one third is identified. A straight or angled surgical curette is used to enucleate as much soft tissue as possible from the periapical area
169
without compromising adjacent structures, specifically the inferior alveolar nerve or maxillary sinus if possible. Removal of the soft tissue is accomplished to reduce bleeding and clear any apical debris that may have been forced out the apex during the initial endodontic treatment. If further enlargement of the bony window is needed, it can be done with the rotary instrument. At this point, removal of the apex is accomplished with either the round or a tapered fissure bur. The authors recommend just reducing the apex from the tip to the desired bevel with a #701 or #702 tapered bur. Two to three millimeters of the apex should be resected. This will reduce the apical bacterial concentration. In addition, the apex is the most unpredictable portion of the root canal system, with multiple foramina and lateral canals that may be unfilled. The removal of 2 to 3 mm of the apex also removes the portion of the root canal system that is usually the most poorly sealed. Ultrasonic preparation requires a small bevel, only 10 to 20 from horizontal (Fig. 3). Minimization of the bevel reduces the amount of dentinal tubules exposed that predispose to apical bacterial leakage. The minimal bevels permitted by the shapes of the ultrasonic tips contribute to the increased success with this technique. Once the root canal filling(s) or other positive apical identifications are made, the root end is prepared to receive the retrograde filling. Hemostasis is
Fig. 3. Use of ultrasonic root-end preparation for maxillary molar.
170
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
critical to precisely prepare the apex and to create a dry environment for the placement of the retrograde filling material. Counted cotton pellets saturated with epinephrine-containing local anesthetic solution are packed tightly into the bony crypt. When exposing the buccal or palatal roots of upper molars, special care is taken not to force any pellets into the maxillary antrum. Usually, two to three pellets are placed and, after waiting 5 minutes, all are removed except for the most deeply placed one. By not removing the pellet in contact with the bone, the bleeding from the marrow spaces remain controlled. If this approach does not provide for complete hemostasis, a small electrosurgical tip can be used to attain hemostasis and to remove the last remnants of granulation tissue. The electrosurgery unit is used with the lowest numerical setting on coagulation to accomplish hemostasis and not burn surrounding bone. This will frequently leave a small hemostatic char that can remain until after the root-end filling is complete. The ultrasonic root preparations are performed with autoclavable ultrasonic tips chosen by the operator on the basis of access to the apical region. Constant irrigation is needed, and for surgical use, it is appropriate to have an assistant irrigate copiously with sterile saline. Using internal systems connected to public water supplies may not provide the level of asepsis required during surgery. The tips are used with gentle pressure in a stroking pattern. Vertical preparation is completed to the bevel on the shaft that will be 2 to 3 mm in depth. Gentle buccal-lingual preparation is done to check for the presence of an isthmus, which is then prepared. An isthmus can be found on any multiple root canal system on the same root. The surgeon should expect to find an isthmus on the mesio-buccal roots of upper molars and frequently on the mesial roots of lower first molars. Engle and Steiman compared isthmus preparation techniques and found adequate removal and sealing only with the use of ultrasonic devices [6]. One major advantage to this technique is that the instrument sizes are smaller the than those of contraangles using burs. This makes nearly all lesions accessible because the average active point length is 3 millimeters. Constant water spray is used on the cutting tip because the tip tends to heat up significantly during use. If not cooled properly, the tip can become hot enough inside the canal to cause gutta percha to melt in the canal with the resultant loss of an endodontic filling. Copious saline spray should be used on the cutting tip with a featherlike back-andforth motion. The attraction of these devices is the versatility of the cutting tips. The universal tip is similar to the end
of a #17 explorer. Two of these are configured to fit into the hard-to-reach apices of molar teeth. There is also a tip for the preparation of an isthmus and a bendable tip that can be adapted to the particular needs of the operator. The angled tips measure 3 mm in length, so an attempt should be made to create the preparation to this depth. Undercutting the preparation is not necessary because of the depth and parallelism of the ultrasonic preparation. After the preparation is complete and before filling, the apex should be irrigated copiously and dried with endodontic paper points. After completion of the root-end filling, a sharp curette is reintroduced into the bony crypt to remove any char from electrosurgical attempts at tissue removal and hemostatic agents used. Bleeding also helps the setting of certain retrograde filling materials, specifically mineral trioxide aggregate (ProRoot MTA, Tulsa Dentsply Endodontics, Tulsa, OK). Micosurgery and magnification Ultrasonic microapical preparation is best performed with the use of magnification. The surgical microscope has become the gold standard of enhanced vision; however, with surgical loupes 3X and 4X power (Designs for Vision, Ronkonkoma, NY), the level of magnification is adequate for these procedures. Magnification of the surgical field enhances the location of the root apex, appropriate preparation, and evaluation of existing root fractures. The presence of an isthmus of necrotic tissue can also be detected with surgical loupes. Specially designed apical mirrors enhance visualization of the apical region. Two types are generally available: hardened, polished stainless steel and ruby.
Cracks and infractions Some authors have reported that the use of ultrasonic devices for apical preparations can create fractures in the root structures [7,8]. Certain early studies by Abedi et al reported root cracking, especially in thinned areas [8]. Their study did not look at different power settings nor the use of irrigation. Other studies have recently compared the root surface after preparation by ultrasonic instruments with various power settings and rotary instruments [9]. These studies indicate that although some chipping occurs with the ultrasonic preparation, no cracks developed. Although the cavosurface margin of the rotary instrument was smoother, it was because of the remnants of the smear layer, which is undesirable. It is accepted
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
171
Fig. 4. Ultrasonic preparation of mid-root perforation.
that the use of ultrasonic devices under medium power settings and adequate irrigation are not directly damaging to the root [10,11]. Von Arx has reported on the use of sonic instruments that use a frequency of 6000 Hz in comparison with ultrasonic instruments with a frequency of 30,000 Hz [12]. His reports with the use of sonic instruments compare favorably with that of the ultrasonic devices. At this time there is no clinical evidence that one has an advantage over the other.
as having a preparation that hermetically seals the root canal system. Microapical preparation provides that and facilitates the surgery by reducing the amount of bone removal. Patients seem to heal faster with less swelling and discomfort. This critical addition to endodontic surgery has made the procedure very predictable, with positive outcomes for many patients. Teeth that were previously condemned for extraction are now able to be routinely saved (Fig. 4).
Conclusion
References
Carr identified the following five major errors of retropreparation that can be reduced or eliminated with the use of the ultrasonic microapical techniques [13]: 1. 2. 3. 4. 5.
Preparation not down the longitudinal axis of the root canal system Preparation lacks significant retention form Preparation lacks proper buccal-lingual extension to assure adequate seal Isthmus area is not prepared and sealed Excessive removal of dentin weakens apical region
The multiple studies comparing one retrograde filling material with another may not be as significant
[1] Mehlhaff DS, Marshall JG, Baumgartner JC. Comparison of ultrasonic/and high-speed-bur root-end preparations using bilaterally matched teeth. J Endod 1997; 23:448 – 52. [2] Lin CP, Chou HG, Kuo JC, Lan WH. The quality of ultrasonic root-end preparation: a quantitative study. J Endod 1998;24:666 – 70. [3] Chailertvanitkul P, Saunders WP, Saunders EM, MacKenzie D. Polymicrobial coronal leakage of super EBA root-end fillings following two methods of rootend preparation. Int Endod J 1998;31:348 – 53. [4] Peters CI, Peters OA, Barabakow F. An in vitro study comparing root-end cavities prepared by diamondcoated and stainless steel ultrasonic retrotips. Int Endod J 2001;34:142 – 8. [5] Rainwater A, Jeansonne BG, Sarkar N. Effects of ultrasonic root-end preparation on microcrack formation and leakage. J Endod 2000;26:72 – 5.
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S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
[6] Engle TK, Steiman HR. Preliminary investigation of ultrasonic root end preparation. J Endod 1995;21: 443 – 5. [7] Min MM, Brown CE, Legan JJ, Kafrawy AH. In vitro evaluation of effects of ultrasonic root-end preparation on resected root surfaces. J Endod 1997;23:624 – 8. [8] Abedi HR, Van Miefio BL, Wilder-Smith P, et al. Effects of ultrasonic root end cavity preparation on the apex. Oral Surg Oral Med Oral Path Endod Radiol 1995;80:207 – 13. [9] Waplington M, Lumley PL, Walmsley AD. Incidence of root face alteration after ultrasonic retrograde cavity preparation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83:387 – 92. [10] Frank RJ, Antrim DD, Bakland LK. Effect of retrograde cavity preparation on root apexes. Endod Dent Traum 1996;12:100 – 3.
[11] Gray GJ, Hatton JF, Holtzmann DJ, et al. Quality of root-end preparations using ultrasonic and rotary instruments in cadavers. J Endod 2000;26:281 – 3. [12] Von Arx T, Kurt B. Root-end cavity preparation after apicoectomy using a new type of sonic and diamondsurfaced retrotip: a 1-year follow-up study. J Oral Maxillofac Surg 1999;57:656 – 61. [13] Carr GB. Ultrasonic root end preparation. Dent Clin NA 1997;41:541 – 54.
Further Reading Von Arx T, Walker WA. Microsurgical instruments for rootend cavity preparation following apicoectomy: a literature review. Endod Dent Traumatol 2000;16: 47 – 62.
Ultrasonic retrograde preparation Stuart E. Lieblich, DMD a,b,*, Bernard McGiverin, DDS, FICD, FACD c a
University of Connecticut Health Center, 236 Farmington Avenue, Farmington, CT 06030, USA, b Avon Oral and Maxillofacial Surgery, 34 Dale Road, Suite 105, Avon, CT 06001, USA c 95 West Entry, Staten Island, NY 10304, USA
The use of ultrasonic devices for apical preparation has dramatically improved the ease of apical surgery and most certainly has contributed to the increase in success rates now reported. Ultrasonic preparation permits a deep retrograde restoration to be placed, one of the key factors to a positive outcome. The ability of these devices to precisely follow the internal root canal anatomy also contributes to this success. Before the development of ultrasonic retropreparation tips, preparation of the apical region was obtained with a rotary instrument. The Hall highspeed turbine drill or a conventional dental handpiece using long-shank friction grip surgical burs were the instruments of choice. A Micro-contra-angle head (Union Broach, Brooklyn, NY) was developed for use on a low-speed straight handpiece. Originally, it was not autoclavable, and many clinicians reported constant gear jamming and difficulty with its use no matter how gently it was handled or lubricated. The use of rotary burs can create preparations that do not follow the long axis of the tooth and, therefore, have decreased apical sealing potential. Off-axis preparation may also sacrifice additional tooth structure and potentially predispose the tooth to root fracture.
Ultrasonic instruments Ultrasonic devices have been used in dentistry for many years for removal of calculus. Applying elec-
* Corresponding author: Avon Oral and Maxillofacial Surgery, 34 Dale Road, Suite 105, Avon, CT 06001. E-mail address: [email protected] (S.E. Lieblich).
trical voltage to piezoelectric ceramics or quartz produces ultrasonic mechanical vibration. The usual frequency is in the range of 30kHz, with a vibration amplitude of 300 mm. Cavitation effects are created with the use of water for an additional physical effect to displace debris and improve cutting efficiency while preventing significant heat formation. Devices are available from many companies (Fig. 1). Advantages of the ultrasonic preparation include the accessibility to the apex, permitting a smaller flap reflection, less bone removal, and less of an apical bevel. Fig. 2 shows the accessibility achieved with an ultrasonic tip at the apex of a tooth. The current piezoelectric, ultrasonic units using stainless steel or diamond-coated autoclavable retrotips allow preparations of the apex for retrofill from a nearly perpendicular approach. Mehlhaff et al compared 76 roots from 29 bilaterally matched pairs of human teeth in cadavers [1]. In the first group, ultrasonic preparations were made in the roots and then filled with amalgam alloy. In the second group, high-speed rotary bur preparations were made in the remaining 50% and filled with the same alloy. The teeth were then extracted and radiographed from both a mesio-distal and bucco-lingual aspect. The same operator performed all the procedures and none of the root-end preparations resulted in perforation. It was determined that the ultrasonic tip produces a deeper root-end preparation with minimum bevel of the root ends. Lin and colleagues studied teeth that were prepared with ultrasonic devices versus rotary instruments [2]. With the aid of image processing, they found the ultrasonic preparations to be more conservative, with less perforations, than those made with the rotary instruments. A study of bacterial leakage by
1042-3699/02/$ – see front matter D 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 9 9 ( 0 2 ) 0 0 0 1 9 - 5
168
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
Fig. 1. Examples of ultrasonic units for apical preparations. All units have autoclavable tips and adjustable power settings.
Chailertvanitkul found significantly more leakage with rotary preparations in comparison with ultrasonic devices [3]. In their study, both groups had the same root-end filling material (super-EBA). Many ultrasonic devices have both stainless steel – and diamond-coated tips for apical preparation. The use of diamond-coated tips permits faster preparation with more gentle pressure. This was verified by Peters, who found a statistically significant reduction in preparation time with the diamond tips in comparison with stainless steel [4]. The diamond tips do remove more dentin and, therefore, should be used carefully to prevent overpreparation. Dye penetration studies that reveal leakage to bacteria
did not show a difference between diamond-coated tips and stainless steel [5].
Flap design Strict adherence to the surgical principles of sharp elevation of a mucoperiosteal flap is essential because perforation of the periosteum can nearly always guarantee hemorrhagic ooze throughout the operation and wound dehiscence afterward. Once the flap is elevated sufficiently, a broad-based retractor such as a Minnesota or Seldin retractor can be used. The McGivern Retractor (W. Lorenz, Jacksonville, FL) is also of
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
Fig. 2. Example of ultrasonic tip for preparation of root apex.
value here because it combines the broad-based end of the Seldin 23 elevator with an ergonomic handle. Care must be taken to keep all retractors firmly situated on the bone to prevent periosteal tearing. Worse yet, impingement on the flap fold can result in ischemia and slough and cause a severe periodontal problem. Surgical technique The high-speed surgical bur (2 mm or #8 round) is used to remove enough cortical bone to expose the apical region. The root apex should not be resected until the full apical one third is identified. A straight or angled surgical curette is used to enucleate as much soft tissue as possible from the periapical area
169
without compromising adjacent structures, specifically the inferior alveolar nerve or maxillary sinus if possible. Removal of the soft tissue is accomplished to reduce bleeding and clear any apical debris that may have been forced out the apex during the initial endodontic treatment. If further enlargement of the bony window is needed, it can be done with the rotary instrument. At this point, removal of the apex is accomplished with either the round or a tapered fissure bur. The authors recommend just reducing the apex from the tip to the desired bevel with a #701 or #702 tapered bur. Two to three millimeters of the apex should be resected. This will reduce the apical bacterial concentration. In addition, the apex is the most unpredictable portion of the root canal system, with multiple foramina and lateral canals that may be unfilled. The removal of 2 to 3 mm of the apex also removes the portion of the root canal system that is usually the most poorly sealed. Ultrasonic preparation requires a small bevel, only 10 to 20 from horizontal (Fig. 3). Minimization of the bevel reduces the amount of dentinal tubules exposed that predispose to apical bacterial leakage. The minimal bevels permitted by the shapes of the ultrasonic tips contribute to the increased success with this technique. Once the root canal filling(s) or other positive apical identifications are made, the root end is prepared to receive the retrograde filling. Hemostasis is
Fig. 3. Use of ultrasonic root-end preparation for maxillary molar.
170
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
critical to precisely prepare the apex and to create a dry environment for the placement of the retrograde filling material. Counted cotton pellets saturated with epinephrine-containing local anesthetic solution are packed tightly into the bony crypt. When exposing the buccal or palatal roots of upper molars, special care is taken not to force any pellets into the maxillary antrum. Usually, two to three pellets are placed and, after waiting 5 minutes, all are removed except for the most deeply placed one. By not removing the pellet in contact with the bone, the bleeding from the marrow spaces remain controlled. If this approach does not provide for complete hemostasis, a small electrosurgical tip can be used to attain hemostasis and to remove the last remnants of granulation tissue. The electrosurgery unit is used with the lowest numerical setting on coagulation to accomplish hemostasis and not burn surrounding bone. This will frequently leave a small hemostatic char that can remain until after the root-end filling is complete. The ultrasonic root preparations are performed with autoclavable ultrasonic tips chosen by the operator on the basis of access to the apical region. Constant irrigation is needed, and for surgical use, it is appropriate to have an assistant irrigate copiously with sterile saline. Using internal systems connected to public water supplies may not provide the level of asepsis required during surgery. The tips are used with gentle pressure in a stroking pattern. Vertical preparation is completed to the bevel on the shaft that will be 2 to 3 mm in depth. Gentle buccal-lingual preparation is done to check for the presence of an isthmus, which is then prepared. An isthmus can be found on any multiple root canal system on the same root. The surgeon should expect to find an isthmus on the mesio-buccal roots of upper molars and frequently on the mesial roots of lower first molars. Engle and Steiman compared isthmus preparation techniques and found adequate removal and sealing only with the use of ultrasonic devices [6]. One major advantage to this technique is that the instrument sizes are smaller the than those of contraangles using burs. This makes nearly all lesions accessible because the average active point length is 3 millimeters. Constant water spray is used on the cutting tip because the tip tends to heat up significantly during use. If not cooled properly, the tip can become hot enough inside the canal to cause gutta percha to melt in the canal with the resultant loss of an endodontic filling. Copious saline spray should be used on the cutting tip with a featherlike back-andforth motion. The attraction of these devices is the versatility of the cutting tips. The universal tip is similar to the end
of a #17 explorer. Two of these are configured to fit into the hard-to-reach apices of molar teeth. There is also a tip for the preparation of an isthmus and a bendable tip that can be adapted to the particular needs of the operator. The angled tips measure 3 mm in length, so an attempt should be made to create the preparation to this depth. Undercutting the preparation is not necessary because of the depth and parallelism of the ultrasonic preparation. After the preparation is complete and before filling, the apex should be irrigated copiously and dried with endodontic paper points. After completion of the root-end filling, a sharp curette is reintroduced into the bony crypt to remove any char from electrosurgical attempts at tissue removal and hemostatic agents used. Bleeding also helps the setting of certain retrograde filling materials, specifically mineral trioxide aggregate (ProRoot MTA, Tulsa Dentsply Endodontics, Tulsa, OK). Micosurgery and magnification Ultrasonic microapical preparation is best performed with the use of magnification. The surgical microscope has become the gold standard of enhanced vision; however, with surgical loupes 3X and 4X power (Designs for Vision, Ronkonkoma, NY), the level of magnification is adequate for these procedures. Magnification of the surgical field enhances the location of the root apex, appropriate preparation, and evaluation of existing root fractures. The presence of an isthmus of necrotic tissue can also be detected with surgical loupes. Specially designed apical mirrors enhance visualization of the apical region. Two types are generally available: hardened, polished stainless steel and ruby.
Cracks and infractions Some authors have reported that the use of ultrasonic devices for apical preparations can create fractures in the root structures [7,8]. Certain early studies by Abedi et al reported root cracking, especially in thinned areas [8]. Their study did not look at different power settings nor the use of irrigation. Other studies have recently compared the root surface after preparation by ultrasonic instruments with various power settings and rotary instruments [9]. These studies indicate that although some chipping occurs with the ultrasonic preparation, no cracks developed. Although the cavosurface margin of the rotary instrument was smoother, it was because of the remnants of the smear layer, which is undesirable. It is accepted
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
171
Fig. 4. Ultrasonic preparation of mid-root perforation.
that the use of ultrasonic devices under medium power settings and adequate irrigation are not directly damaging to the root [10,11]. Von Arx has reported on the use of sonic instruments that use a frequency of 6000 Hz in comparison with ultrasonic instruments with a frequency of 30,000 Hz [12]. His reports with the use of sonic instruments compare favorably with that of the ultrasonic devices. At this time there is no clinical evidence that one has an advantage over the other.
as having a preparation that hermetically seals the root canal system. Microapical preparation provides that and facilitates the surgery by reducing the amount of bone removal. Patients seem to heal faster with less swelling and discomfort. This critical addition to endodontic surgery has made the procedure very predictable, with positive outcomes for many patients. Teeth that were previously condemned for extraction are now able to be routinely saved (Fig. 4).
Conclusion
References
Carr identified the following five major errors of retropreparation that can be reduced or eliminated with the use of the ultrasonic microapical techniques [13]: 1. 2. 3. 4. 5.
Preparation not down the longitudinal axis of the root canal system Preparation lacks significant retention form Preparation lacks proper buccal-lingual extension to assure adequate seal Isthmus area is not prepared and sealed Excessive removal of dentin weakens apical region
The multiple studies comparing one retrograde filling material with another may not be as significant
[1] Mehlhaff DS, Marshall JG, Baumgartner JC. Comparison of ultrasonic/and high-speed-bur root-end preparations using bilaterally matched teeth. J Endod 1997; 23:448 – 52. [2] Lin CP, Chou HG, Kuo JC, Lan WH. The quality of ultrasonic root-end preparation: a quantitative study. J Endod 1998;24:666 – 70. [3] Chailertvanitkul P, Saunders WP, Saunders EM, MacKenzie D. Polymicrobial coronal leakage of super EBA root-end fillings following two methods of rootend preparation. Int Endod J 1998;31:348 – 53. [4] Peters CI, Peters OA, Barabakow F. An in vitro study comparing root-end cavities prepared by diamondcoated and stainless steel ultrasonic retrotips. Int Endod J 2001;34:142 – 8. [5] Rainwater A, Jeansonne BG, Sarkar N. Effects of ultrasonic root-end preparation on microcrack formation and leakage. J Endod 2000;26:72 – 5.
172
S.E. Lieblich, B. McGiverin / Oral Maxillofacial Surg Clin N Am 14 (2002) 167–172
[6] Engle TK, Steiman HR. Preliminary investigation of ultrasonic root end preparation. J Endod 1995;21: 443 – 5. [7] Min MM, Brown CE, Legan JJ, Kafrawy AH. In vitro evaluation of effects of ultrasonic root-end preparation on resected root surfaces. J Endod 1997;23:624 – 8. [8] Abedi HR, Van Miefio BL, Wilder-Smith P, et al. Effects of ultrasonic root end cavity preparation on the apex. Oral Surg Oral Med Oral Path Endod Radiol 1995;80:207 – 13. [9] Waplington M, Lumley PL, Walmsley AD. Incidence of root face alteration after ultrasonic retrograde cavity preparation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83:387 – 92. [10] Frank RJ, Antrim DD, Bakland LK. Effect of retrograde cavity preparation on root apexes. Endod Dent Traum 1996;12:100 – 3.
[11] Gray GJ, Hatton JF, Holtzmann DJ, et al. Quality of root-end preparations using ultrasonic and rotary instruments in cadavers. J Endod 2000;26:281 – 3. [12] Von Arx T, Kurt B. Root-end cavity preparation after apicoectomy using a new type of sonic and diamondsurfaced retrotip: a 1-year follow-up study. J Oral Maxillofac Surg 1999;57:656 – 61. [13] Carr GB. Ultrasonic root end preparation. Dent Clin NA 1997;41:541 – 54.
Further Reading Von Arx T, Walker WA. Microsurgical instruments for rootend cavity preparation following apicoectomy: a literature review. Endod Dent Traumatol 2000;16: 47 – 62.