Fixed functional appliance treatment and avascular necrosis

Abstract

We read with interest the Ask Us section in the April issue regarding the role of the lateral pterygoid muscle in functional orthopedic treatment (Kuftinec MM, Voudouris JC. Am J Orthod Dentofacial Orthop 2004;125(4):19A) and felt the need to comment on some of the statements made, because they directly addressed our research.Drs Kuftinec and Voudouris state that fixed functional appliance treatment “has been shown through magnetic resonance imaging to be associated with severe condylar avascular necrosis and severe disk displacement in a significant part of the human sample.” To underline their statement, they cite our study with Herbst subjects.1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google ScholarFirst, we must point out that we never drew that conclusion. Of course, everybody is free to draw his own conclusions based on the results presented. However, changing conclusions or omitting information to make the results suit a different interpretation is far from good scientific practice.In our article,1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar we presented 2 patients with disc displacements. Both had disc displacements without reduction upon mandibular opening, and both displacements were already present before treatment was started. In another study,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar we even demonstrated that Herbst treatment did not induce disc displacement in any subject with a normal pretreatment disc position. It is not true that Herbst treatment is associated with severe disc displacement.The study1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar cited by Drs Kuftinec and Voudouris contains images of Herbst subjects showing signs of condylar modeling as a result of bite jumping. They obviously interpreted these modeling signs as condylar avascular necrosis. Actually, we wondered how they could draw that conclusion based on the data in the article.In good clinical practice, a certain diagnosis can never be established based on a diagnostic image alone. To establish a diagnosis, the clinical findings must coincide with the findings on the diagnostic image; if not, a certain pathologic condition can only be presumed. However, in the article under discussion, no data (about pain, movement restriction, occlusal disturbances) were presented that would have allowed the diagnosis of condylar avascular necrosis.According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (www.niams.nih.gov/hi/topics/avascular_necrosis/), “in the early stages of avascular necrosis, the patients may not have any symptoms. As the disease progresses, however, most patients experience joint pain—at first, only when putting weight on the affected joint, and then even when resting. Pain usually develops gradually and may be mild or severe. If avascular necrosis progresses and the bone and surrounding joint surface collapse, pain may develop or increase dramatically… . The period of time between the first symptoms and loss of function is different for each patient, ranging from several months to more than a year.”As stated above, the article under discussion1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar did not contain any useful clinical data. In another article,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar the temporomandibular joint (TMJ) function of Herbst patients was analyzed. The observation period was 1.6 years and thus longer than the time between the first symptoms and the loss of function for avascular necrosis. In this Herbst sample,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar from before treatment to 1 year after treatment, the prevalence of intracapsular inflammation decreased from 24% to 7% of the joints. From the start of Herbst treatment until the end of the observation period (1.6 years), no patient reported TMJ pain, implying that all intracapsular inflammations 1 year after Herbst treatment were subclinical. Furthermore, the prevalence of structural bony changes (osteoarthrosis, deviations in form) of the condyle decreased from 14% of the joints before treatment to 3% after treatment. Thus, the development of pain and structural bony changes in the Herbst patients was opposite to what would have been expected for avascular necrosis.Furthermore, if due to avascular necrosis the mandibular condylar surface breaks down, it results in a loss of vertical dimension and consequently in occlusal disturbances in form of anterior or anterolateral open bites.3Schellhas K.P. Piper M.A. Omlie M.R. Facial skeleton remodeling due to temporomandibular joint degeneration: an imaging study of 100 patients.Craniomand Pract. 1992; 10: 248-259PubMed Google Scholar The Herbst patients under discussion, however, all had normal overjet and overbite after treatment.1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar, 2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google ScholarThus, we can conclude that no single clinical parameter supports the diagnosis of condylar avascular necrosis.Drs Kuftinec and Voudouris also wrote that our study1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar “should serve as a beacon of risk, pointing to the dangers of exceeding the adaptive capabilities of the muscles, bones, and soft tissues.” However, as stated above, there is no risk for TMJ dysfunction associated with Herbst treatment. This has recently also been proven histologically.4McNamara J.A. Peterson J.E. Pancherz H. Histologic changes associated with the Herbst appliance in adult rhesus monkeys (Macacca mulatta).Semin Orthod. 2003; 9: 26-40Abstract Full Text PDF Scopus (23) Google Scholar Thus, there is no need for regular imaging of the TMJ area during or after Herbst treatment to keep with the “safe play.” We read with interest the Ask Us section in the April issue regarding the role of the lateral pterygoid muscle in functional orthopedic treatment (Kuftinec MM, Voudouris JC. Am J Orthod Dentofacial Orthop 2004;125(4):19A) and felt the need to comment on some of the statements made, because they directly addressed our research. Drs Kuftinec and Voudouris state that fixed functional appliance treatment “has been shown through magnetic resonance imaging to be associated with severe condylar avascular necrosis and severe disk displacement in a significant part of the human sample.” To underline their statement, they cite our study with Herbst subjects.1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar First, we must point out that we never drew that conclusion. Of course, everybody is free to draw his own conclusions based on the results presented. However, changing conclusions or omitting information to make the results suit a different interpretation is far from good scientific practice. In our article,1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar we presented 2 patients with disc displacements. Both had disc displacements without reduction upon mandibular opening, and both displacements were already present before treatment was started. In another study,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar we even demonstrated that Herbst treatment did not induce disc displacement in any subject with a normal pretreatment disc position. It is not true that Herbst treatment is associated with severe disc displacement. The study1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar cited by Drs Kuftinec and Voudouris contains images of Herbst subjects showing signs of condylar modeling as a result of bite jumping. They obviously interpreted these modeling signs as condylar avascular necrosis. Actually, we wondered how they could draw that conclusion based on the data in the article. In good clinical practice, a certain diagnosis can never be established based on a diagnostic image alone. To establish a diagnosis, the clinical findings must coincide with the findings on the diagnostic image; if not, a certain pathologic condition can only be presumed. However, in the article under discussion, no data (about pain, movement restriction, occlusal disturbances) were presented that would have allowed the diagnosis of condylar avascular necrosis. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (www.niams.nih.gov/hi/topics/avascular_necrosis/), “in the early stages of avascular necrosis, the patients may not have any symptoms. As the disease progresses, however, most patients experience joint pain—at first, only when putting weight on the affected joint, and then even when resting. Pain usually develops gradually and may be mild or severe. If avascular necrosis progresses and the bone and surrounding joint surface collapse, pain may develop or increase dramatically… . The period of time between the first symptoms and loss of function is different for each patient, ranging from several months to more than a year.” As stated above, the article under discussion1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar did not contain any useful clinical data. In another article,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar the temporomandibular joint (TMJ) function of Herbst patients was analyzed. The observation period was 1.6 years and thus longer than the time between the first symptoms and the loss of function for avascular necrosis. In this Herbst sample,2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar from before treatment to 1 year after treatment, the prevalence of intracapsular inflammation decreased from 24% to 7% of the joints. From the start of Herbst treatment until the end of the observation period (1.6 years), no patient reported TMJ pain, implying that all intracapsular inflammations 1 year after Herbst treatment were subclinical. Furthermore, the prevalence of structural bony changes (osteoarthrosis, deviations in form) of the condyle decreased from 14% of the joints before treatment to 3% after treatment. Thus, the development of pain and structural bony changes in the Herbst patients was opposite to what would have been expected for avascular necrosis. Furthermore, if due to avascular necrosis the mandibular condylar surface breaks down, it results in a loss of vertical dimension and consequently in occlusal disturbances in form of anterior or anterolateral open bites.3Schellhas K.P. Piper M.A. Omlie M.R. Facial skeleton remodeling due to temporomandibular joint degeneration: an imaging study of 100 patients.Craniomand Pract. 1992; 10: 248-259PubMed Google Scholar The Herbst patients under discussion, however, all had normal overjet and overbite after treatment.1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar, 2Ruf S. Pancherz H. Does bite-jumping damage the TMJ? A prospective longitudinal clinical and MRI study of Herbst patients.Angle Orthod. 2000; 70: 183-199PubMed Google Scholar Thus, we can conclude that no single clinical parameter supports the diagnosis of condylar avascular necrosis. Drs Kuftinec and Voudouris also wrote that our study1Ruf S. Pancherz H. Temporomandibular joint remodeling in adolescents and young adults during Herbst treatment: a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation.Am J Orthod Dentofacial Orthop. 1999; 115: 607-618Abstract Full Text Full Text PDF PubMed Scopus (158) Google Scholar “should serve as a beacon of risk, pointing to the dangers of exceeding the adaptive capabilities of the muscles, bones, and soft tissues.” However, as stated above, there is no risk for TMJ dysfunction associated with Herbst treatment. This has recently also been proven histologically.4McNamara J.A. Peterson J.E. Pancherz H. Histologic changes associated with the Herbst appliance in adult rhesus monkeys (Macacca mulatta).Semin Orthod. 2003; 9: 26-40Abstract Full Text PDF Scopus (23) Google Scholar Thus, there is no need for regular imaging of the TMJ area during or after Herbst treatment to keep with the “safe play.” Ask usAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 125Issue 4Preview Full-Text PDF Authors' responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 126Issue 3PreviewIt is always good to note the interest that our writing stimulates. Even more so when that interest comes from 2 prominent clinical researchers, Drs Ruf and Pancherz. In this case, our German colleagues chimed in with a heavy hand. Full-Text PDF