Relationship Between TMJ Disorders and Malocclusion

Oviya V J1, Saravana Dinesh S P*2, Deepa Gurunathan3 1Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 162, Poonamallee High Road, Chennai 600077, Tamil Nadu, India 2Department of Orthodontics and Dentofacial Orthopedics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 162, Poonamallee High Road, Chennai 600077, Tamil Nadu, India 3Department of Pedodontics and preventive dentistry, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 162, Poonamallee High Road, Chennai 600077, Tamil Nadu, India


INTRODUCTION
Temporomandibular disorders (TMD) are de ined by American Academy of Orofacial Pain (AAOP) as a collective term embracing a number of clinical com-plaints related to the muscles of mastication, temporomandibular joint and/or associated with orofacial structures (Firestone, 1997).
The TMJ and its associated structures play an essential role in mandibular movements and also help in the distribution of stress produced by various actions such as chewing, swallowing and speaking (Grif iths, 1983). Such TMJ disorders cause a series of symptoms and signs in the population including painful joint sounds, restricted mouth opening, deviation of the mandible, pain in the muscles of mastication etc., (Tanaka et al., 2008) The etiology of TMD is multifactorial, including systemic, psychological and structural factors (Mohlin et al., 1991). One of such factors is malocclusion which can be considered predisposing for TMJ disorders (Egermark-Eriksson et al., 1983). Previous reports showed controversial results regarding the TMD and malocclusion relationship (Michelotti and Iodice, 2010;Zonnenberg and Mulder, 2013).
Few studies reported the association between TMJ disorders and craniofacial anomalies such as open bite, cross bite, excessive overjet (Egermark-Eriksson et al., 1990;Mohlin et al., 1991). However, some reported less in luence on the signs and symptoms of TMD even after orthodontic correction of anomalies (Larsson and nnerman, 1981;Pilley et al., 1997) Only limited studies have been conducted in patients of all age groups. Previously our team has conducted numerous cross-sectional studies (Felicita et al., 2012;Rubika et al., 2015;Krishnan et al., 2018), clinical trials (Jain et al., 2014;Felicita, 2017a;Samantha et al., 2017), invitro studies (Kumar et al., 2011;Dinesh et al., 2013;Kamisetty et al., 2015;Sivamurthy and Sundari, 2016;Vikram et al., 2017), case reports (Felicita, 2017b(Felicita, , 2018, literature reviews (Krishnan and Pandian, 2015;Viswanath et al., 2015) over the past many years. Now we are focussing on epidemiological surveys. Hence, an attempt has been made in this study to assess the relationship of TMD and malocclusion among patients of the Chennai population.

Sampling
This study was conducted in a university setting. The study samples were chosen from the patients visiting a hospital in Chennai from June (2019) -March (2020).

Data collection
The retrospective study was carried out among patients of all ages. Data collection was done through reviewing records of 86000 patients between June (2019) -March (2020). Data such as patient's age, gender, symptoms associated with TMD, presence of malocclusion, patient's pro ile were noted. The data collected were cross veri ied with intraoral photographs.

Inclusion criteria
Patients of all ages who reported with one or more TMJ problems

Exclusion criteria
Patients with systemic diseases, development abnormalities, parafunctional habits, traumatic injuries in dentofacial region, history of orthodontic management were excluded.
Incomplete/censored data were excluded too.

Data analysis
The data collected was entered into the excel sheet. Data was analysed through frequency and Chisquare tests using SPSS software.

RESULTS AND DISCUSSION
A total of 294 patients reported to the hospital with TMJ problems. The mean age of the study population was 33.4. Majority of the study population (58.36%) belonged to the age group of 20-40yrs (Graph 1). The X-axis shows the age group distribution and Y-axis shows the distribution of the study population. There was a higher incidence of TMJ disorders in the age group of 20-40years(58.36%purple).
About 50.68% of the patients presented with a straight pro ile, 33.56% with a convex and 15.75% with a concave pro ile (Graph 3). Patients with straight pro ile (50.68%-violet) were more prevalent followed by convex (33.56%-pink) and concave (15.75%-dark blue).
In the present study, 54.79% of the patients who reported with TMJ problems had malocclusion (Graph 4). Prevalence of malocclusion was higher among the patients with TMJ disorders (54.79%blue).
There is an increased prevalence of malocclusion among patients of age group 20-40yrs (Graph 5).
There is no signi icant difference in the prevalence of malocclusion between different genders (Graph 6). The X-axis shows the gender distribution and Y-axis shows the distribution of the study population.
Pain (38.91%) and joint clicking (38.91%) were the highest reported TMJ symptoms among the study population (Graph 7). The X-axis shows the TMJ symptoms, and Y-axis shows the patient's count. Pain (38.91%-green) and Clicking joints (38.91%grey) were the most common symptoms reported among the study population.
There is a signi icant increase in the presence of malocclusion among the patients with joint clicking (Graph 8). Graph 5 shows the X-axis shows the age group distribution and Y-axis shows the distribution of the study population. There was a higher incidence of TMJ disorders in the age group of 20-40 years (31.51%-blue) which was however not statistically signi icant(Chi-square test;χ2=0.223, df=3, p-Value= 0.974 (>0.05)).
Since there is an unclear opinion in malocclusion being an etiologic factor of TMD, it is essential to study the extent of its contribution to TMD. Hence, this study was intended to evaluate any association between different aspects of malocclusion and TMD. In the present study, patients with history of development abnormalities, parafunctional habits, traumatic injuries in the dentofacial region and history of previous orthodontic management were excluded to rule out the effects of those on TMJ.
In this study, 294 patients had reported with TMJ symptoms from June 2019 to March 2020. A study by Muthukrishnan et al (Muthukrishnan and Sekar, 2015) in the Chennai population reported TMD in the patients with a prevalence rate of 53.7%.
In the present study, males showed higher prevalence of TMD compared to females, however it is not statistically signi icant. Many previous studies reported a higher incidence of TMD among females than males (Schmid-Schwap et al., 2013;Chisnoiu et al., 2015) as women are more sensitive to pain conditions than males.
In this study, TMD was more prevalent in the age group of 20-40 yrs. This is in accordance with the study by Muthukrishnan et al (Muthukrishnan and Sekar, 2015) who reported higher prevalence of TMD among patients belonging to 18-30 years of age. However, a study by Glass et al (Glass et al., 1993) reported higher prevalence of TMD with increase in age.
In the present study, pain and clicking joints were the most common symptoms reported in patients with TMD. This is in accordance with many other studies that reported similar indings (Al-Gadhaan et al., 2018;Al-Khotani et al., 2016;Jang et al., 2016).
About 54.79% of the patients with TMJ problems reported the presence of malocclusion in this study. This study showed association between malocclusion and TMD. These results are in accordance with many studies that reported a signi icant relationship of malocclusion in TMD (Egermark-Eriksson et al., 1990;Gesch et al., 2004;Sánchez-Pérez et al., 2013;Sujatha et al., 2018). However, few studies reported results that are contradicting the present study (Godoy et al., 2007;Aboalnaga et al., 2019).
Orthodontic treatment at an earlier age is necessary to reduce the progress of TMJ disorders. Few studies have shown a signi icant reduction in the prevalence of TMD by orthodontic treatment (Olsson and Lindqvist, 1992;Henrikson, 1999). A study by Larsson et al (Larsson and nnerman, 1981) reported that patients who had received orthodontic treatment were less severely affected by TMD than those people who had not undergone orthodontic manage-ment. Solberg et al (Solberg et al., 1986) studied the TMJ changes in young adults through autopsy and concluded that malocclusion was associated with morphological changes in the TMJ.

Limitations
This study has several limitations. Since this is a retrospective study, the sample size is very less and is limited to certain geographical locations. Parameters such as characteristics of malocclusion and its features were not included. Hence, cohort study with the inclusion of these parameters among a larger population is required.

CONCLUSIONS
Within the limits of this study, there is an association in the incidence of TMD among the patients with malocclusion. Oral health intervention programs are needed to screen/diagnose orthodontic issues and TMJ disorders in order to identify and offer treatment preventing it from progressing to severe disorders.