December, 2011

Morphological study of temporomandibular joint in orthodontically treated patients by using pre-treatment and post treatment orthopantomographs

Contributors:

1. Dr Shashikumar H. C. MDS,
Reader, Department of Orthodontics & Dentofacial Orthopedics,
Shri Raja Rajeshwari institute of Dental sciences
Bangalore, Karnataka, India

2. Dr Sujala G. Durgekar , MDS
Assistant Professor, Department of Orthodontics & Dentofacial Orthopedics,
KLE Vishwanath Katti Institute of Dental Sciences,
KLE University, J.N.M.C. Campus, Nehru Nagar,
Belgaum, Karnataka, India.

3. Dr K. Nagaraj, MDS,(Corresponding Author)
Reader, Department of Orthodontics & Dentofacial Orthopedics,
KLE Vishwanath Katti Institute of Dental Sciences,
KLE University, J.N.M.C. Campus, Nehru Nagar,
Belgaum, Karnataka, India.

4. Dr Divyakant A. Acharya, MDS
Orthodontist,
Private practitioner,
Mumbai, India.

ABSTRACT:

The comparison of the condylar morphology was done in individuals before and after orthodontic treatment and the relationship between the orthodontic treatment and temporomandibular joint dysfunction (TMD) was assessed. There was no statistical association in the morphology of condylar among the groups. It was concluded that orthodontic treatment does not cause TMD.

INTRODUCTION:

The relationship between orthodontic treatment and temporomandibular joint dysfunction has been widely discussed in the literature^1-13. Orthodontists have been both accused of causing and complimented for curing temporomandibular disorders (TMD).  To better understand the origin of these conflicting opinions, many papers were published. Most of these publications were viewpoint articles and case reports which had little or no value in the assessment of the relationship between TMDs and orthodontic treatment⁴. Since 1988 there have been many sample studies^{1-3and 5-9} which   conclude that orthodontic treatment has no connection with TMD, while some studies report that it may help alleviate the symptoms¹⁴ of TMD.

Orthodontic treatment involving retraction of the maxillary incisors is said to position the condyle posteriorly and hence cause TMD. A clinical study¹⁵ based on forty two Class II division I cases concluded that changes in the condylar position was not correlated with incisor retraction. Comparing orthodontic patients with untreated controls may also not be valid, because orthodontic patients may have more TMJ problems than individuals with more normal occlusions^{7, 16}.

Today, there still remains a debate over whether the orthodontic treatment causes TMD or not. So this study was undertaken to compare the morphology of the condyle in individuals before and after orthodontic treatment using orthopantomograph (OPG) and to study the relationship between the orthodontic treatment and TMD.

MATERIAL AND METHOD:

The subjects for the present study consisted of records of 150 orthodontically treated patients in the Department of Orthodontics and Dentofacial Orthopaedics, KLES’ Institute of Dental Sciences, Belgaum, Karnataka, India. The selected subjects belonged to the age group 10-20 years. They had undergone orthodontic treatment for a period of 1-2 years. Pre orthodontic treatment and post-treatment orthodontic orthopantomographs were selected of these patients from the record room.

As this was a retrospective study a strict protocol was followed in selecting the orthopantomographs. The OPGs were evaluated with special emphasis on the mandibular condyles. Each radiograph was examined to verify its image quality. Those with distortions were discarded and new patient records were selected. Fifty subjects were excluded because of the poor quality of their radiographs.

The final study group consisted of 100 subjects.

The study group was divided into two groups

• Group 1 consisted of 50 patients (25 males and 25 females), who underwent extraction of upper and lower first premolars for orthodontic treatment.
• Group 2 consisted of 50 patients (25 males and 25 females), who underwent non-extraction orthodontic treatment.

The same 100 subjects were also divided based on age group into two groups.

• Group1 consisted of 50 patients with age group below 15 years
• Group 2 consisted of 50 patients above 15 years.

The OPGs were evaluated by three qualified examiners from the Department of Oral Medicine and Radiology, KLES’ Institute of Dental Sciences, Belgaum, India.

The examiners were asked to observe the morphology of the condyles on each OPG and assess them for the following radiological abnormalities:

1. Flattening of the articular surface.
2. Sub-cortical sclerosis.
3. Osteophytes.
4. Micro-cysts.
5. Marginal erosion.

After evaluation of each radiograph, they were scored according to the following criteria:

0 – No radiological abnormalities detected.

1 – Only one type of radiological abnormality detected.

2 – More than one type of radiological abnormality detected.

More than one radiological variation could be found within one individual. For every OPG the mean score was calculated by dividing the total score by the number of the examiners. For intra-examiner reproducibility, 25 randomly chosen radiographs were evaluated again one month after their first examination and the coefficient of correlation was calculated. The coefficient of correlation was 0.9 which showed that the examiners could repeat their previous choices fairly consistently.

The chi square test was used to compare the change in condylar morphology between various sub-groups of the study sample .Various sub-groups for study were: pre-treatment and post-treatment groups, male and female subjects groups and extraction and non- extraction treatment groups. The last subgroup was based on the age of the subjects above and below 15 years.

RESULTS:

The radiological variation in each of these subgroups is summarized as follows:

1. Comparison of pretreatment and post treatment OPG: Among all the radiological variations, flattened articular surface (8%, Fig 1a and 1b) and subcortical sclerosis (3%, Fig 2a and 2b) showed highest frequency of occurrence in the OPGs taken after orthodontic treatment. While marginal erosion (2%, Fig 3a and 3b), osteophytes (0%), microcysts (1%) showed minimum frequency of occurrence after orthodontic treatment (Table 1).

The most commonly observed radiological variation was flattened articular surface (8%). It was found that there was an increase in the number of radiological variations in the condyles of post-treatment OPGs (14%) in comparison to pre-treatment OPGs (3%).

However this finding was not statistically significant [P > 0.05]

2.  Comparison of condylar variation among different gender: Radiological variations in female samples were slightly higher condylar variations (16%) in comparison to the male group. No statistically significant correlation could be drawn between condylar variation and sex [P = 0.08] (Table 2)

3. Comparison of condylar variation in subjects with different treatment protocol. The study revealed that there was no statistically significant association between extraction and condylar variations. Radiological variations within each extraction and non extraction group showed only 14% of condylar changes [P= 0.08] (Table 3)

4. Comparison of condylar variation in different age group subjects:    Individuals above 15 years of age showed higher condylar changes after treatment (18%) in comparison to individuals below 15 years (10%), but this was a statistically insignificant finding  [P = 0.52] (Table 4)

DISSCUSION:

One of the contributing factors to TMDs, which has been strongly debated for many years, is the occlusal condition. It is stated that orthodontic therapy may be a possible etiological factor. The deleterious effects of orthodontic mechanics in the stomatognathic system could be due to new occlusal design with the premolar extraction and incisor retraction, causing posterior displacement of the condyle and consequent over load of pain sensitive areas.

In the last decade much effort has been made to clarify the relationship between orthodontic treatment and TMD. In the recent years there has been resurgence in the controversy about extractions for orthodontic purposes, fueled mainly by considering it as a risk factor for TMDs. In a radiological study¹⁷ it was concluded that orthodontic treatment does not cause any radiological changes in TMJ. In our study condylar variation in the pre-treatment radiographs showed only 3% changes and post-treatment radiographs showed 14% condylar changes. There was no statistical association between pre-treatment and post-treatment condylar changes.

In few studies^18-19 it was stated that females are more prone to morphologic changes in their condyles than males and hence more susceptible for TMD. In an investigation²⁰ it was found that the females in the untreated group had significantly more condylar abnormalities than males (p < 0.001). This could be due to higher levels of joint laxity, emotional stress and presence of specific pain receptors that are proposed as predisposing factors. The variations in the females may, thus, be so common that factors such as orthodontic treatment or malocclusion do not cause them to increase. In our study females showed 16% of condylar changes and males showed 12% of condylar changes in post-treatment OPGs but this difference was not statistically significant.

As several years had elapsed since the completion of the orthodontic treatment, detailed information about their orthodontic treatment was not available. For this reason it was not possible to compare the radiological findings with the orthodontic mechanics used. Neither was it possible to estimate how successful the orthodontic treatment had been, because the occlusion was not examined. In our study, the number of radiographic variations in the subjects treated by extraction mechanotherapy is significantly higher than subjects treated by non-extraction. However, it is not possible to say whether these are related to orthodontic treatment, to functional or morphological changes, or to the skeletal dysplasia that led to orthodontic treatment⁴.

In a study²¹ it was found that adults are at a greater risk to TMDs and show more condylar changes than adolescents because adolescents have better TMJ adaptability. In our study subjects above 15 years (18%) showed a slight increase in the number of condylar changes when compared to subjects below 15 years (12%) but this difference was of no statistical significance.

Of all different severe radiological variations, flattened articular surface (8%) was more common followed by subcorticular sclerosis (3%). Arthritic changes such as marginal erosion (2%) which is due to inflammation were not found more frequently in orthodontically subjects. Osteophytes (0%) were not found in our subjects. But all the radiological variations (14%) observed were statistically insignificant.

Here, we have used panoramic radiographs (OPG) to assess condylar morphology. Panoramic radiographs have become widely used in dental offices and are readily accepted by patients. It provides screening of bony structures of the condyles. In addition, it provides a broad coverage of the oral region for radiographic interpretation. Several studies^{10, 22} have concluded that OPG is suitable for the examination of condyles, though it reveals a lower level of involvement than tomography. The major disadvantage of panoramic radiographs is that the resultant image does not resolve fine anatomical detail that may be seen in other radiographs like MRI, CT scan and tomography²³. The muscular strength and endurance is associated with TMD^24-25 .Other factors like ethnic background, socioeconomic status, psychological status, age and the sex of the subjects, type of appliance and placebo effects are also known to influence the prevalence and incidence of TMD⁴. A strict protocol of all these factors should be considered to formulate the study group for the study. The difficulty when evaluating association between malocclusions and TMD is that there is individual fluctuation of signs and symptoms of TMD when subjects are followed longitudinally^11-13.Prevalence aswell as severity may vary between recordings made on different occasions.

There is still a need for well-designed longitudinal studies to evaluate the association between TMD and orthodontic treatment.

CONCLUSION:

The finding from this study can be briefly put as:

1. There was no statistical association between orthodontic treatment and radiological changes in the condyle.
2. The treatment protocol [with or without extraction] didn’t have any statistical association with the change in the morphology of condylar.
3. There was no statistical association between sex and age of orthodontic patient and radiological changes in their condyles.
4. Of the different radiological variations in the condyle, flattened articular surface and sub-cortical sclerosis showed significant difference in orthodontically treated patients.

Based on the present study it can be concluded that orthodontic treatment does not cause TMD. As the orthodontic profession evolves over the next few years, responsibility for the treatment of the TMJ will become a major part of our specialty. It is, therefore, incumbent upon us to be particularly attuned to the TMJ prior, during and after comprehensive orthodontic treatment to ensure functionally and physiologically successful orthodontic treatment results.

References:

1. Dahl B. L., Krogstad B S, Ogaard B.Signs and symptoms of cariomandibular disorders in two groups of 19- year old individuals, one treated orthodontically and the other not. Acta Odontologica Scandinavica 1988;46:89-93
2. Smith A, Freer T J. Post orthodontic occlusal function. Australian Dental Journal. 1989; 34: 301-9
3. Dibbets J M H, Van der Weele L Th .Prevalence of TMJ symptoms and X- ray findings. . European Journal of Orthodontics 1989; 11:31-6
4. Reynders R M. Orthodontics and temporomandibular disorders: A review of the literature (1966-1988). Am J Orthod Dentofac Orthop 1990; 97:463-71
5. Egermark-Eriksson I, Carlsson G E, Magnusson T, Thilander B. A longitudinal study on malocclusion in relation to signs and symptoms of cranio-malocclusion disorders in children and adolescent . Eur J Orthod 1990; 12:399-407
6. Sadowsky C, Theisen T A, Sakols E I. Orthodontic treatment and temporomandibular joint sounds – A longitudinal study. Am J Orthod Dentofac Orthop. 1991; 99: 441-47
7. Dibbets J M H, van der Weele L Th. Extraction, orthodontic treatment, and craniomandibular dysfunction. Am J Orthod Dentofac Orthop. 1991; 99: 210-19
8. Hirata RH, Heft MW, Hernandez B, King G J. Longitudinal study of signs of temporomandibular disorders (TMD) in orthodontically treated and nontreated groups. Am J Orthod Dentofac Orthop. 1992; 101: 35-40.
9. Rendell J K, Norton L A, Gay T. Orthodontic treatment and temporomandibular disorders. Am J Orthod Dentofac Orthop. 1992; 101: 84-7

10. Peltola S. Radiological variations in mandibular condyles of Finnish students, one group orthodontically treated and the other not. Eur J of Orthod. 1993; 15:223-27.

11. Egermark I, Magnusson T, Carlsson G E. A 20 year follow – up of signs and symptoms of temporomandibular disorders and malocclusion in subjects with and without orthodontic treatment in childhood. Angle Orthod 2003; 73:109-15

12. Egermark I, Carlsson G E, Magnusson T. Prospective long term study of signs and symptoms of temporomandibular disorders in patients who received orthodontic treatment in childhood. Angle Orthod 2005; 75: 645-50.

13. Macfarlane T V, Kenealy P, Kingdon A, Mohlin B O, Piley J R, Richmond S etal. Twenty – year cohort study of health gain from orthodontic treatment: temporomandibular disorders. Am J Orthod Dentofac Orthop. 2009;135:692-3

14. Egermark I, Thilander B .Craniomandibular disorders with special reference to orthodontic treatment: An evaluation from childhood to adulthood. Am J Orthod Dentofac Orthop.1992;101:28-34

15. Luecke PE, Johnson LE. The effect of maxillary first premolar extraction and incisor retraction on mandibular: Testing the central dogma of ‘functional orthodontics.’ Am J Orthod Dentofac Orthop. 1992;101:4-12.

16. Luther F. Orthodontics and the temporomandibular joint: Where are we now? Part 1. Orthodontic treatment and temporomandibular disorders. Angle Orthod. 1998; 68:295-304

17. Dibbets JMH. Temperomandibular joint dysfunction and craniofacial growth – A statistical analysis. Stafleu and Tholen, Leiden, Netherlands 1977.

18. Oberg T. Carlsson, Fajers. The mandibular joint- A morphologic study on human autopsy material. Octa Odont Scan 1971; 29:349-84.

19. Solberg WK, Bibb, Hanson T, Nordstrom B. Malocclusion associated with temporomandibular changes in young adults at autopsy. Am J Orthop Dentofac Orthop. 1986; 89:226-30.

20. Henrikson T, Nilner M, Kurol J. Signs of temporomandibular disorders in girls receiving orthodontic treatment-A prospective and longitudinal comparisons with untreated Class II malocclusion and normal occlusion subjects. Eur J Orthod 2000; 22:271-81.

21. Wanman A, Agerberg G. Mandibular dysfunction in adolescents-I Prevalence of symptoms. Octa Odontol Scand 1986; 44:47-54.

22. Larheim T A, Johannessen S, Tveito L. Abnormalities of temporomandibular joint in adult with rheumatic disease. A comparison of panoramic, transcranial and transpharyngeal radiography with tomography. Dentomaxillofacial Radiology 17: 109-13

23. Uotilo E. Temporomandibular joint in adult rheumatoid arthritis. A clinical and roentgenologic study. Acta Odontologica Scandinavica 1964; 22(suppl 39 ):1-9

24. Mohlin B, Pilley JR, Shaw WC, Kingdon A. A survey of craniomandibular disorders in 1000 12 year olds .Study design and baseline data in a follow up study. Eur J Orthod. 1991; 13:111-13

25. Mohlin B, Derweduwen K, Pilley R, Kingdon A, Shaw WC, Kenealy P. Malocclusion and temporomandibular disorder: A comparison of adolescents with moderate to severe dysfunction with those without signs and symptoms of temporomandibular disorders and their further development to 30 years of age. Angle Orthod .2004; 74:319-27.

Tags: TMD, tmj