«Trevor P. Bodine, D.D.S. An Abstract Presented to the Graduate Faculty of Saint Louis University in Partial Fulfillment of the Requirements for the ...»
IMPACT ON CONDYLAR GROWTH FOLLOWING MITEK ANCHOR
TEMPOROMANDIBULAR JOINT DISC REPOSITIONING
Trevor P. Bodine, D.D.S.
Presented to the Graduate Faculty of
Saint Louis University in Partial Fulfillment
of the Requirements for the Degree of
Master of Science in Dentistry
Purpose: To better understand the growth effects of surgical repositioning and stabilization of anteriorly displaced articular discs using the Mitek mini-anchor system in an adolescent patient. Methods: The sample consisted of pre- and post-surgical records of 22 patients diagnosed with idiopathic condylar resorption (ICR) and anterior temporomandibular disc displacement, collected from one private practice clinician. The treated sample was compared to 22 untreated control subjects matched for age, sex, Angle classification, and mandibular plane angle. Presurgical (T1 and T2) and post-surgical (T3 and T4) mandibular tracings were superimposed on natural stable structures. Horizontal, vertical and absolute changes in the cephalometric landmark condylion (Co) were evaluated to determine growth and treatment effects. After superimpositions were completed, x and y coordinates for Co were plotted and the change in the coordinates measured to evaluate growth. Results: The treated group showed an overall mean decrease in condylar height pre-surgically and statistically significant differences between the presurgical and post-surgical vertical change. Patients in the treated group showed no significant differences in growth of the condyle post-surgically when compared with the matched control group. Conclusions: Adolescent patients treated by surgical use of the Mitek anchor to reposition internally deranged discs, show no adverse condylar growth effect following surgery.
IMPACT ON CONDYLAR GROWTH FOLLOWING MITEK ANCHOR
TEMPOROMANDIBULAR JOINT DISC REPOSITIONING
IN ADOLESCENTSTrevor P. Bodine, D.D.S.
A Thesis Presented to the Graduate Faculty of Saint Louis University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Dentistry
COMMITTEE IN CHARGE OF CANDIDACY:
DEDICATIONThis work is dedicated to my family and parents who have shown unconditional love and support for me throughout this journey.
To my darling wife Courtney, there are no words that can convey what you mean to me. Your endless love, patience and untold sacrifices for us will never be forgotten. You are my rock, my comfort and I would not be half the man I am today if it were not for you. You are a truly magnificent mother and role model for our daughter, Madeline.
To my beautiful daughter Madeline, you have enriched my life beyond my wildest dreams. Seeing you smile when you see my face or hear my voice melts my heart and your unconditional love gives me the strength to keep persevering.
To my selfless parents, Mike and Ginny, you have given me everything that I have ever needed in life to be successful and yet you keep giving. Your love, support and sacrifice for your children is immeasurable and I am only now beginning to understand the breadth of it.
This project could not have been completed without the help
and support of the following individuals:
Dr. Peter Buschang, thank you for your guidance and enthusiasm throughout this endeavor. Thank you for your passion for research, commitment to excellence and for challenging me to constantly think for myself.
Dr. Eustaquio Araujo, thank you for your work and guidance on this project. You have taught me many things over the last two years about this trade, balancing life’s passions, and most importantly bringing out the best in people.
Dr. Donald Oliver, thank you for your thoroughness and attention to detail on this project. You have taught me the importance of the little things and I will carry that with me throughout my career.
Dr. Larry Wolford, without your passion for knowledge this project would never have happened. Thank you and your staff for your hospitality in welcoming me into your practice and allowing me the use of your records.
List of Tables
List of Figures
CHAPTER 1: INTRODUCTION
CHAPTER 2: REVIEW OF THE LITERATUREMandibular growth
Temporomandibular joint dysfunction............19 TMD effects on condylar growth.................21 Idiopathic condylar resorption.................30 Mitek mini-anchor system
Statement of the thesis
CHAPTER 3: JOURNAL ARTICLEAbstract
Materials and Methods
Reliability of measurements...............59 Statistical analysis
Summary and Conclusions
Table 3.1: Age descriptive statistics for treatment and control subjects
Table 3.2: Cephalometric landmarks
Table 3.3: Comparison of the change in Co pre-surgically and post-surgically within the treatment group
Table 3.4: Pre-surgical change in Co for the treatment and control groups
Table 3.5: Post-surgical change in Co for the treatment and control groups
Table 3.6: Correlation between MPA and change in Co.
Figure 2.1: Histological section of a growing mandibular condylar cartilage
Figure 2.2: (A) Normal TMJ anatomy,(B)Anteriorly displaced TMJ disc relationship.
..............21 Figure 2.3: (A) Cross section of a condyle with the Mitek mini-anchor system in place,(B)Posterior view
Figure 3.1: Custom cephalometric analysis.
................55 Figure 3.2: Post-surgical cephalometric radiograph........57 Figure 3.3: Post-surgical superimposition.................57 Figure 3.4: Coordinate reference plane
Figure 3.5: Pre-surgical change in Co
Figure 3.6: Post-surgical change in Co
Figure 3.7: Horizontal change in Co
Figure 3.8: Vertical change in Co
Contemporary orthodontic therapy entails much more than just straightening teeth. Patients now seek out the services of an orthodontist for everything from a crooked front tooth to debilitating joint disease. The modern orthodontist must be equipped with the knowledge and tools necessary to treat such conditions as they present themselves.
Temporomandibular joint dysfunction (TMD) has become a frequent complaint of orthodontic patients, especially female patients. Joint problems can manifest themselves in many forms, from simple clicking noises on opening to debilitating migraines and joint pain. Partial anterior displacement of the articular disc is the most common sign of joint dysfunction, affecting nearly 40% of the general population.1 Displacement of the disc can occur at any time of life; it usually follows a traumatic event that causes the condyle-disc relationship to be altered. Adolescent patients are susceptible to this derangement, especially during their rapidly changing growth phases.
While many treatment modalities have been devised to alleviate the symptoms of TMJ dysfunction, few therapies are routinely used to correct the actual disease process. A new treatment modality that exists for the correction of an anteriorly displaced disc utilizes the Mitek mini-anchor system, which is tethered to the posterior zone of the disc and embedded in the posterior neck of the condyle. This surgical procedure is limited to severe cases of disc displacement and idiopathic condylar resorption.
TMJ surgery is an aggressive procedure when preformed at any age, but especially when surgically exposing the joint of an adolescent. Concerns have to be raised about the ramifications of surgically manipulating the condyle during the growing years. Previous studies have shown the procedure to have positive results for stability and elimination of TMD symptoms; however the risks of negatively effecting further mandibular growth must be taken into account when deciding if the procedure is warranted.
The aim of this current study is to assess pre- and post-surgical growth of the condyle in adolescent patients treated with the Mitek mini-anchor system to recapture an anteriorly displaced articular disc. The study will assess the pre-surgical state of growth in patients diagnosed with idiopathic condylar resorption (ICR) and in comparison to age and sex matched controls to see if there is any effect on condylar growth. Diminished condylar growth is expected in the treatment group compared to that of the untreated control group due to the ill effects of derangement. The study will also assess the condylar growth that follows successful reorientation of the condyle-disc relationship by use of the Mitek mini-anchor system in the treated group. The reapproximation of the appropriate disc-condyle relationship will be assessed to determine if the growth rate of the condyle has been altered post-surgically.
The foregoing review of the literature will start by discussing mandibular growth principles from a historical perspective. This will be followed by a review of the role that the condylar apparatus plays in the growth of the lower jaw. The condyle and condylar cartilage more specifically, have been postulated to be the site of the most active growth of the mandible. The physical relationship between the condyle and the articular disc, and its effect on the growth of the lower jaw, will also be discussed. This will be followed by a review of temporomandibular joint dysfunction and the effects this pathologic condition has on condylar growth. The review of the pertinent literature for the study will conclude with a look at what is currently known regarding the Mitek anchor and its use in orthognathic surgery. Finally, a description of the actual surgical procedure to recapture the displaced disc will be reviewed.
The first reports of mandibular growth can be traced back over 200 years. Mandibular growth was historically thought to be in a forward and downward direction through bony growth of the chin. Through the innovative use of alizarin dyes in 1771, John Hunter2, an English anatomist, showed that the mandible grows largely by depositing new bone along the posterior border of the ramus; the anterior border undergoes minor resorption. He first described the currently held theory that the mandible grows in an upward and backward direction instead of strictly growing at the chin.
Almost a century later in 1864, Humphry3 experimentally confirmed this new concept to over-all growth of the lower jaw by inserting small metallic rings in the anterior and posterior borders of the mandibular rami of young pigs. The rings placed in the posterior aspect became more embedded in bone while the anteriorly placed rings eventually fell out of the bone as the anterior surface was resorbed. This concept of upward and backward growth, along with downward and forward displacement, resulting from the continued growth of the craniofacial complex and the articulating temporal bone, ushered in a new era focusing on the growth of the ramus and condyle.
The shift in focus to the back of the mandible as the driving force for growth led to two key studies in the early 20th century that furthered the understanding of the role of the mandibular condyle. Charles4 and Brodie5 both showed that the mandibular condyle is an important growth location and that its development is associated with the downward and forward growth of mandible. They were also able to show that the condyle grew at a rate proportional to the increases in cortical bone along the posterior border of the ramus and alveolar heights of the mandibular body. In their landmark 1964 paper, Enlow and Harris6 mapped out the histological characteristics of both the interior and exterior surfaces of the mandible. The basic regional growth and remodeling patterns of the mandible were established in their study and the mandible was shown to follow the expanding ―V‖ principle of remodeling. This principle involves the addition of new bone on the interior portion of the V, and removal of bone occurs on the outer portion, resulting in actual movement of the entire area towards the open end of the V. Through this principle, Enlow showed that condylar growth paces the posterior movement of the ramus; the neck is being continuously relocated in a cephaloposterior direction as it follows behind the moving condyle.
Originally thought to function as an epiphyseal plate of cartilage4,7, much like that of a long bone, the mandibular condyle was assumed to undergo cartilaginous proliferation and interstitial growth of the cartilage followed by boney replacement: thus elongating the bone. In his address to the 43rd Annual Meeting of the American Association of Orthodontists in October 1946, Sicher8 explained how the growth of the mandible, growth of both the cartilage and the growth of the bone played dual roles in making the mandible as a whole grow. He addressed the common idea that the condylar cartilage was either an articular cartilage or an epiphyseal cartilage. He stated that the mandibular condylar cartilage grows by interstitial cartilaginous growth, as in an epiphyseal cartilage of a long bone, and through appositional growth from the deep layers of the fibrous connective tissue covering, like an articular cartilage. This hybrid growth of the condyle, part interstitial, part appositional, is key to further understanding the growth of the mandible.