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GINGIVAL RETRACTION: Authors' response
L E T T E R S
LETTERS
J
ADA welcomes letters from readers on articles that have appeared in The Journal. The Journal reserves the right to edit all communications and requires that all letters be signed. Letters must be no more than 550 words and must cite no more than five references. No illustrations will be accepted. A letter concerning a recent JADA article will have the best chance of acceptance if it is received within two months of the article’s publication. For instance, a letter about an article that appeared in April JADA usually will be considered for acceptance only until the end of June. You may submit your letter via e-mail to “jadaletters@ ada.org”; by fax to 1-312-440-3538; or by mail to 211 E. Chicago Ave., Chicago, Ill. 60611-2678. By sending a letter to the editor, the author acknowledges and agrees that the letter and all rights of the author in the letter sent become the property of The Journal. The views expressed are those of the letter writer and do not necessarily reflect the opinion or official policy of the Association. Brevity is appreciated. INSPIRED
I am so impressed. Having finished reading Dr. Björn Zachrisson’s November JADA’s Master Clinician feature, “Planning Esthetic Treatment After Avulsion of Maxillary Incisors” (JADA 2008;139[11]: 1484-1490), I just had to write. This is the type of article I wish we had more of in JADA. Sure, some of us may really be interested in fluorosis and palatine rugae patterns, but truly healing a dental “cripple,” as reported by Dr. Zachrisson, is something that inspires me to dream once again and to reflect upon how wonderful it is to be a practicing dentist.
Don’t get me wrong. I hope I never see someone like this walk into my practice. On the other hand, I am so proud to know that I am a part of a profession made up of individuals dedicated to helping people and treating their dental maladies, whether they are simple or as complex as this particular one. I needed a lift today, and JADA just gave it to me. Earl Lord, DDS Cornville, Ariz.
GINGIVAL RETRACTION
In their October JADA article, “Gingival Retraction Techniques for Implants Versus Teeth” (JADA 2008;139[10]: 1354-1363), Dr. Vincent Benanni and colleagues reviewed and compared gingival retraction techniques used for teeth and their relevance and suitability for implant impressions (polyvinyl siloxane and computer-aided design/ computer-aided manufacturing). Their article was well-written and thoroughly researched. I have several comments to add. One technique not mentioned is the use of a hollow impression coping as a retraction sleeve to temporarily deflect the tissue prior to taking the impression. The coping typically is plastic, which will not nick or damage the implant surface and can be used as a punch if the tissue has overlapped the margins of the implant. The stability of a well-fitting and secure healing cap also will determine the gingival health of the periimplant apparatus. Finally, the authors mention several times the potential of a “deeply placed” implant. This article underscores the decision process to use a screw-retained restoration or custom abutment JADA, Vol. 140
with an accessible margin for cement cleanup. Harvey Jay Mahler, DDS Chicago
Authors’ response: We thank Dr. Mahler for his letter. He raises an interesting point regarding the use of hollow impression copings as retraction sleeves prior to impressiontaking, which we believe poses some issues. As stated in our article, the use of an implant-level pickup technique does not normally require gingival retraction. However, some existing onepiece implant systems involve capturing a tissue-level impression at the implant fixture level prior to fabricating the definitive coronal restoration (Straumann, Basel, Switzerland). Snap-on impression copings extend beyond the already seated internal Morse taper-connected abutment. Scacchi and coworkers1 reviewed this system. The use of prefabricated plastic impression copings (or, alternatively, customized sleeves to provide retraction) inevitably is associated with causing some degree of trauma to the soft tissues, since it is difficult to control the level of force exerted during their placement, particularly with the “snap-on” prefabricated approach. Such force is likely to be much greater than that induced by retraction with injectable matrices. Around natural teeth, the use of copper bands as retraction sleeves causes an incisional wound in the junctional epithelium, which heals after about four days.2 The absence of a periodontal ligament around implants and the relative lack of an organized fibrous architecture within peri-implant muhttp://jada.ada.org
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
February 2009
143
L E T T E R S
cosa might contraindicate this technique, especially in the presence of a thin biotype.3,4 A further issue associated with the use of plastic impression copings is the fit of the resulting restoration. Accuracy of fit is reliant on many factors, among them a high level of machine tolerance or compliance of component connections between the coping, the implant fixture and the laboratory implant analogue. Snap-on plastic copings are affected by the elastic memory of plastic and the ability of the plastic to recover completely. Indirect metal impression copings may offer greater accuracy than direct plastic copings,5 which is of greatest importance where multiple units are involved. However, misfit strain measurements comparing indirect metal copings with direct snap-on copings provided acceptable results, supporting a direct impression technique6 (given the limitations of strain gauge placement on framework spans as a measure of casting fit). On the other hand, a review assessing implant impression techniques found conflicting evidence between a direct snap-on coping approach and the indirect pickup impression method.7 Dr. Mahler has raised an interesting issue. He was referring to the use of impression copings only in the capacity of a retraction sleeve, but to give a more complete answer, we have addressed the possible issues involved when these sleeves are used as a direct impression coping. Vincent Bennani, DDS, PhD Senior Lecturer
Donald Schwass, BSc, BDS 144
JADA, Vol. 140
http://jada.ada.org
Postgraduate Student in Prosthodontics
Nicholas Chandler, BDS, MSc, PhD Associate Professor Department of Oral Rehabilitation University of Otago School of Dentistry Dunedin, New Zealand 1. Scacchi M, Merz BR, Schär AR. The development of the ITI DENTAL IMPLANT SYSTEM, part 2: 1998-2000–steps into the next millennium. Clin Oral Implants Res 2000;11(suppl 1):22-32. 2. Ruel J, Schuessler PJ, Malament K, Mori D. Effect of retraction procedures on the periodontium in humans. J Prosthet Dent 1980;44 (5):508-515. 3. Ahmad I. Anterior dental aesthetics: gingival perspective. Br Dent J 2005;199(4): 195-202. 4. Ericsson I, Lindhe J. Probing depth at implants and teeth: an experimental study in the dog. J Clin Periodontol 1993;20(9): 623-627. 5. Walker MP, Ries D, Borello B. Implant cast accuracy as a function of impression techniques and impression material viscosity. Int J Oral Maxillofac Implants 2008;23(4): 669-674. 6. Cehreli MC, Akça K. Impression techniques and misfit-induced strains on implantsupported superstructures: an in vitro study. Int J Periodontics Restorative Dent 2006;26 (4):379-385. 7. Lee H, So JS, Hochstedler JL, Ercoli C. The accuracy of implant impressions: a systematic review. J Prosthet Dent 2008; 100(4):285-291.
A SECOND OPINION
I found the new “Clinical Dilemmas” feature in October JADA interesting. Dr. Frank Spear offers his opinion concerning the etiology for “A Patient With Severe Wear on the Anterior Teeth and Minimal Wear on the Posterior Teeth” (JADA 2008;139[10]:13991403). I would offer another opinion. This patient has a Class II retrognathic bite, and is most likely a mouth breather with a tongue thrust swallow, and the posterior teeth never fully erupted. Given his bruxism history and acid reflux symptoms, there is a high probability that he has obstructive sleep apnea and should undergo a sleep study.
Larry Z. Lockerman, DDS TMJ/Headache Center & Sleep Disorders Center UMass Memorial Medical Center Worcester, Mass.
Author’s response: The hypothesis that forward posturing of retrognathic mandibles is a compensating mechanism for obstructive sleep apnea (OSA) and can lead to occlusions such as that illustrated in my article is currently under study, although I am not aware of any conclusive findings. There are two studies1,2 that seem to indicate that anterior open bite is the more probable result of OSA in growth. It does make empirical sense that the body would position the mandible in a forward position to open the airway. It follows that a braced forward position against anterior teeth would provide greater stability than simple forward posturing. Because this braced position could produce more time with teeth in contact than would bruxing or clenching, it could conceivably produce wear such as that seen in these photos. In researching this response, I was informed that early results of a pilot study3 show that patients with OSA given nonrestrictive bite appliances saw their OSA get worse. The study is too small to draw conclusions, but the loss of a braced position and seating of the condyles in centric relation could be the reason why the OSA worsened. If Dr. Lockerman’s point is to consider OSA as a possible causative or contributing factor, I believe he is absolutely correct. I would certainly recommend a sleep study if other details of the medical history point to sleep-disordered breathing.
February 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
LETTERS
J
ADA welcomes letters from readers on articles that have appeared in The Journal. The Journal reserves the right to edit all communications and requires that all letters be signed. Letters must be no more than 550 words and must cite no more than five references. No illustrations will be accepted. A letter concerning a recent JADA article will have the best chance of acceptance if it is received within two months of the article’s publication. For instance, a letter about an article that appeared in April JADA usually will be considered for acceptance only until the end of June. You may submit your letter via e-mail to “jadaletters@ ada.org”; by fax to 1-312-440-3538; or by mail to 211 E. Chicago Ave., Chicago, Ill. 60611-2678. By sending a letter to the editor, the author acknowledges and agrees that the letter and all rights of the author in the letter sent become the property of The Journal. The views expressed are those of the letter writer and do not necessarily reflect the opinion or official policy of the Association. Brevity is appreciated. INSPIRED
I am so impressed. Having finished reading Dr. Björn Zachrisson’s November JADA’s Master Clinician feature, “Planning Esthetic Treatment After Avulsion of Maxillary Incisors” (JADA 2008;139[11]: 1484-1490), I just had to write. This is the type of article I wish we had more of in JADA. Sure, some of us may really be interested in fluorosis and palatine rugae patterns, but truly healing a dental “cripple,” as reported by Dr. Zachrisson, is something that inspires me to dream once again and to reflect upon how wonderful it is to be a practicing dentist.
Don’t get me wrong. I hope I never see someone like this walk into my practice. On the other hand, I am so proud to know that I am a part of a profession made up of individuals dedicated to helping people and treating their dental maladies, whether they are simple or as complex as this particular one. I needed a lift today, and JADA just gave it to me. Earl Lord, DDS Cornville, Ariz.
GINGIVAL RETRACTION
In their October JADA article, “Gingival Retraction Techniques for Implants Versus Teeth” (JADA 2008;139[10]: 1354-1363), Dr. Vincent Benanni and colleagues reviewed and compared gingival retraction techniques used for teeth and their relevance and suitability for implant impressions (polyvinyl siloxane and computer-aided design/ computer-aided manufacturing). Their article was well-written and thoroughly researched. I have several comments to add. One technique not mentioned is the use of a hollow impression coping as a retraction sleeve to temporarily deflect the tissue prior to taking the impression. The coping typically is plastic, which will not nick or damage the implant surface and can be used as a punch if the tissue has overlapped the margins of the implant. The stability of a well-fitting and secure healing cap also will determine the gingival health of the periimplant apparatus. Finally, the authors mention several times the potential of a “deeply placed” implant. This article underscores the decision process to use a screw-retained restoration or custom abutment JADA, Vol. 140
with an accessible margin for cement cleanup. Harvey Jay Mahler, DDS Chicago
Authors’ response: We thank Dr. Mahler for his letter. He raises an interesting point regarding the use of hollow impression copings as retraction sleeves prior to impressiontaking, which we believe poses some issues. As stated in our article, the use of an implant-level pickup technique does not normally require gingival retraction. However, some existing onepiece implant systems involve capturing a tissue-level impression at the implant fixture level prior to fabricating the definitive coronal restoration (Straumann, Basel, Switzerland). Snap-on impression copings extend beyond the already seated internal Morse taper-connected abutment. Scacchi and coworkers1 reviewed this system. The use of prefabricated plastic impression copings (or, alternatively, customized sleeves to provide retraction) inevitably is associated with causing some degree of trauma to the soft tissues, since it is difficult to control the level of force exerted during their placement, particularly with the “snap-on” prefabricated approach. Such force is likely to be much greater than that induced by retraction with injectable matrices. Around natural teeth, the use of copper bands as retraction sleeves causes an incisional wound in the junctional epithelium, which heals after about four days.2 The absence of a periodontal ligament around implants and the relative lack of an organized fibrous architecture within peri-implant muhttp://jada.ada.org
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
February 2009
143
L E T T E R S
cosa might contraindicate this technique, especially in the presence of a thin biotype.3,4 A further issue associated with the use of plastic impression copings is the fit of the resulting restoration. Accuracy of fit is reliant on many factors, among them a high level of machine tolerance or compliance of component connections between the coping, the implant fixture and the laboratory implant analogue. Snap-on plastic copings are affected by the elastic memory of plastic and the ability of the plastic to recover completely. Indirect metal impression copings may offer greater accuracy than direct plastic copings,5 which is of greatest importance where multiple units are involved. However, misfit strain measurements comparing indirect metal copings with direct snap-on copings provided acceptable results, supporting a direct impression technique6 (given the limitations of strain gauge placement on framework spans as a measure of casting fit). On the other hand, a review assessing implant impression techniques found conflicting evidence between a direct snap-on coping approach and the indirect pickup impression method.7 Dr. Mahler has raised an interesting issue. He was referring to the use of impression copings only in the capacity of a retraction sleeve, but to give a more complete answer, we have addressed the possible issues involved when these sleeves are used as a direct impression coping. Vincent Bennani, DDS, PhD Senior Lecturer
Donald Schwass, BSc, BDS 144
JADA, Vol. 140
http://jada.ada.org
Postgraduate Student in Prosthodontics
Nicholas Chandler, BDS, MSc, PhD Associate Professor Department of Oral Rehabilitation University of Otago School of Dentistry Dunedin, New Zealand 1. Scacchi M, Merz BR, Schär AR. The development of the ITI DENTAL IMPLANT SYSTEM, part 2: 1998-2000–steps into the next millennium. Clin Oral Implants Res 2000;11(suppl 1):22-32. 2. Ruel J, Schuessler PJ, Malament K, Mori D. Effect of retraction procedures on the periodontium in humans. J Prosthet Dent 1980;44 (5):508-515. 3. Ahmad I. Anterior dental aesthetics: gingival perspective. Br Dent J 2005;199(4): 195-202. 4. Ericsson I, Lindhe J. Probing depth at implants and teeth: an experimental study in the dog. J Clin Periodontol 1993;20(9): 623-627. 5. Walker MP, Ries D, Borello B. Implant cast accuracy as a function of impression techniques and impression material viscosity. Int J Oral Maxillofac Implants 2008;23(4): 669-674. 6. Cehreli MC, Akça K. Impression techniques and misfit-induced strains on implantsupported superstructures: an in vitro study. Int J Periodontics Restorative Dent 2006;26 (4):379-385. 7. Lee H, So JS, Hochstedler JL, Ercoli C. The accuracy of implant impressions: a systematic review. J Prosthet Dent 2008; 100(4):285-291.
A SECOND OPINION
I found the new “Clinical Dilemmas” feature in October JADA interesting. Dr. Frank Spear offers his opinion concerning the etiology for “A Patient With Severe Wear on the Anterior Teeth and Minimal Wear on the Posterior Teeth” (JADA 2008;139[10]:13991403). I would offer another opinion. This patient has a Class II retrognathic bite, and is most likely a mouth breather with a tongue thrust swallow, and the posterior teeth never fully erupted. Given his bruxism history and acid reflux symptoms, there is a high probability that he has obstructive sleep apnea and should undergo a sleep study.
Larry Z. Lockerman, DDS TMJ/Headache Center & Sleep Disorders Center UMass Memorial Medical Center Worcester, Mass.
Author’s response: The hypothesis that forward posturing of retrognathic mandibles is a compensating mechanism for obstructive sleep apnea (OSA) and can lead to occlusions such as that illustrated in my article is currently under study, although I am not aware of any conclusive findings. There are two studies1,2 that seem to indicate that anterior open bite is the more probable result of OSA in growth. It does make empirical sense that the body would position the mandible in a forward position to open the airway. It follows that a braced forward position against anterior teeth would provide greater stability than simple forward posturing. Because this braced position could produce more time with teeth in contact than would bruxing or clenching, it could conceivably produce wear such as that seen in these photos. In researching this response, I was informed that early results of a pilot study3 show that patients with OSA given nonrestrictive bite appliances saw their OSA get worse. The study is too small to draw conclusions, but the loss of a braced position and seating of the condyles in centric relation could be the reason why the OSA worsened. If Dr. Lockerman’s point is to consider OSA as a possible causative or contributing factor, I believe he is absolutely correct. I would certainly recommend a sleep study if other details of the medical history point to sleep-disordered breathing.
February 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.