Lack of fusion between the frontonasal and maxillary processes causes clefts through the lip, alveolus, and floor of the nose in people with cleft lip. Cleft palate is a birth defect that occurs when the palatal shelves of the maxillary processes do not fuse together properly, resulting in a split in either the roof of the mouth or palatal velum. The precise location at which they show up is governed by the areas of the face in which the fusion of different facial processes did not take place. This, in turn, is impacted by the point in an embryo's life at which some form of interference with development took place. ¹

Patients with cleft lip and palate, as well as their parents, give greater importance to the surgical correction of cleft anomalies and less importance to the other concerns related to oral health, and structural co-ordination skeletal as well as dental malocclusion. ²

Malocclusion is an abnormality that causes disfigurement or gets in the way of function. It needs to be corrected if the disfigurement or function problem is likely to hurt the patient's physical or mental health. ³

Certain functional issues could arise if there is an interference or deviation in the occlusion or the occlusal plane that becomes more pronounced and starts to resemble the slope of the articular eminence of the temporomandibular joint. 1) Loss of canine occlusion, 2) Loss of incisal guidance, and 3) the emergence of interference with functioning and non-working posterior dental function. Pullinger et al., (1993) stated that people with Temporomandibular joint disorder (TMD) may be more likely to have occlusal factors like a large horizontal overlap, minimal vertical overlap, anterior skeletal open bite, unilateral posterior crossbite, occlusal slides greater than 2 mm, and no teeth in posterior region. ⁴ Crossbites and Class III malocclusion are the most common occlusal abnormalities as compared to class II malocclusion affecting the craniomandibular structures. ⁵

“TMD is a group of orofacial disorders characterized by pain in the preauricular area, TMJ or muscles of mastication, limitations and deviations in the range of motion of the lower jaw, and sounds in the TMJ during functioning of the jaw, according to Laskin et al.'s 1983 definition of TMD (American Dental Association, 1983).”. ⁶ TMD is thought to be multifactorial in nature. TMD symptoms include muscular pain, deviation or deflection of the lower jaw, locking of the jaw, and the presence of clicking sounds when opening and closing the mouth. ⁷ Untreated malocclusions, unstable occlusions, stress and other psychologic reasons, trauma, individual predispositions, and structural abnormalities are only a few of the theories put forth to explain the aetiology of TMD. ⁸

Finding a less complicated and quicker techniques for diagnostic method of TMD in primary care would be useful. A common clinical diagnostic tool for TMDs is the Helkimo Index. ⁹ It is a simplified assessment that evaluates joint function, joint discomfort, and mandibular mobility and its restrictions while movement. ¹⁰

The treatment in cleft is limited to dental correction, skeletal correction with orthognathic surgery. But the functional correction is still a query in the cleft cases. There are limited evidences available where in the TMJ was evaluated for the TMD in cleft. With this hypothesis, thus the following study was planned to evaluate the occurrence of temporomandibular disorder in cleft patients.

The aim of this study is to evaluate and compare adult instances of Unilateral cleft lip and palate (UCLP) and non-cleft class I for the presence and severity of abnormalities in the temporomandibular joints using Helkimo index.

Statistical analysis was done by using descriptive and inferential statistics using Chi square test and student’s unpaired t test and p<0.05 was considered as level of significance.

In Group I, 10% cases showed no symptoms of TMD, 40% cases showed mild symptoms. Among the severe symptoms 10% showed difficulty in mouth opening, 10% cases showed mandibular dislocation along with its painful movement and 30% showed pain the TMJ region and in the masticatory muscles. Locking of the jaw was not present in the cases.

In Group II, 60% cases showed no symptoms of TMD, 40% cases showed mild symptoms and no cases showed severe symptoms. This was found to be statistically significant with p value (p=0.018), chi square test ϗ2-value was 17.14. ( Table 1, Figure 1)

In Group I, 35% of cases showed mild symptoms of TMD, 30% cases showed moderate symptoms and 35% cases showed severe symptoms. In Group II, 25% cases showed no symptoms of TMD, 70% cases showed mild symptoms and 5% showed moderate symptoms. This was found to be statistically significant with p value (p=0.0005), chi square test ϗ2-value was 17.90. ( Table 2, Figure 2)

In Group I, the mean value of Helkimo dysfunction score was 7.50 with mean standard deviation of 4.08, mean standard error 0.91. In Group II, the mean value of Helkimo dysfunction score was observed 1.65 with standard deviation of 1.42, standard mean error 0.31. This was found to be statically significant with p value (p=0.0001) and student unpaired t value 6.04. ( Table 3, Figure 3)

Clefts arise during the fourth developmental stage. Orofacial clefts are typically classified as either cleft lip with or without cleft palate or cleft palate only. Malocclusion may be associated with one or more of the following: malalignment of individual teeth in each arch, mismatch of dental arches relative to the normal occlusion (in antero-posterior, vertical, or transverse planes), or lack of posterior teeth. Patients with TMD have been said to have higher rates of occlusal characteristics like a significant overjet, a small overbite, and a lack of anterior teeth.

Helkimo analysis was done only on the number of patients participated in the study, not on the basis of sex and gender differentiation (both male and female were taken into consideration in the study) to assess the occurrence of TMD in cleft patients.

In this study on evaluation and comparison with the Helkimo anamnestic index, it was found that 10% of group 1 had no symptoms of TMD (Ai0), which might be due to the absence of crowding in the anterior arch and the absence of crossbite in both the anterior and posterior, that is, both the upper and lower teeth were coordinated. 40 % reported mild TMD symptoms (Ai1). It could be a sign of the presence of TMJ sounds, jaw stiffness, or jaw tiredness (clicking). These cases might have a lesser fibrosis of muscle fiber, which causes less contraction and relaxation of muscle, which leads to jaw fatigue and stiffness. Muscle stiffness causes a shift in the orientation of the condyle during downward and forward movement of the mandible, resulting in TMJ clicking. Among severe cases (AI 2), 10% had difficulties in mouth opening, which could be suggestive of a decrease in range of mouth opening (normal range > 40 mm) and agenesis of teeth. There were no cases where the patient experienced lockjaw. Furthermore, 10% had mandibular dislocation and painful movements, which might be the result of the presence of crossbite in the posterior and anterior, which leads to severe constriction of the maxillary arch, which changes the orientation of the muscle fiber as well as the orientation of the condyle.

While 30% of the patients had painful TMJ regions and/or masticatory muscles, which might be due to the presence of grinding and clinching habits, an imbalance in the muscles of mastication caused by excessive teeth grinding is a typical cause of TMJ discomfort.

When Group 2 were assessed for occurrence of TMD using Helkimo anamnestic index, and 40% of the cases had mild symptom while 60% had no symptoms at all.

Helkimo dysfunction index evaluation, it was found that 35% of Group 1 had mild symptoms of TMJ dysfunction (Di1), which could be due to pain during mandibular movement while wide opening of the mouth causes stretches in muscle fiber and condylar ligaments. Furthermore, 30% experienced moderate TMD symptoms (Di 2), which were thought to be caused by tenderness in the temporomandibular joint while palpating the lateral side of the TMJ. Pain while performing lateral movements, as well as a wide opening of the mandible. While palpation of masticatory muscles at 1-3 sites (masseter and temporalis muscles) may reveal tenderness as the jaw closes, the upper and lower arches are not in sync. which could lead to the presence of a clicking sound in the TMJ in one joint or both joints.

35% had a severe symptom of TMD (Di 3), due to the presence of tenderness during palpation of the posterior side of the TMJ. Because the posterior part of the articular disc is made up of nerves and vessels, compression causes TMJ pain. A lack of occlusal harmony in the upper and lower arch causes canine guidance discord and TMJ pain when performing two or more mandibular movements, such as lateral movement of the mandible.

The prevalence of TMD in Group 2 was evaluated using the Helkimo dysfunction score. Because their jaws were in harmony with crowing less than 2mm, 25% had no symptoms of TMD (Di0). 70% of the 14 cases had a mild symptom of TMD (Di1), which could be due to anterior crowding and a single tooth crossbite. Further, 5% of the patients had moderate TMD symptoms (Di 2), which were assumed to be due to the presence of moderate crowding in the anterior and proclination of the upper and lower anterior teeth, whereas a severe case of TMD was not present.

In comparison of the Helkimo dysfunction score between two groups (the mean value was calculated for dysfunction). The statistics suggested that the mean of 7.50 was the cumulative result of the assessments done for Ai and Di, suggesting a high occurrence of TMD in Group 1. As for Group 2, the mean of 1.65 indicates that TMD is not common there. Thus, it was found that out of 20 UCLP cases, 7 had mild symptoms, 6 had moderate symptoms, and 7 had severe symptoms, demonstrating that TMD can develop in unilateral cleft lip and palate.

On evaluation for the dysfunction component of Helkimo, cases with no symptoms of TMD were higher in group 2 in comparison to Group 1. The mild symptom of TMD was also higher in Group 2 in comparison to Group 1. While moderate symptoms of TMD were higher in Group 1 in comparison to Group 2, severe symptoms of TMD were also found to be higher in Group 1 in comparison with Group 2.

Even the mean dysfunction score in group 1 was higher than in group 2, indicating that craniofacial malformations such as deformity of the jaw, dentition, and soft tissue in cleft lip and palate cases resulting in disfigurement and malocclusion from mild to severe grade can lead to TMDs that must be addressed depending on the severity of the occurrence of TMDs.

On evaluation of the anamnestic component and dysfunction component of the Helkimo index, the UCLP group shows higher occurrences of temporomandibular disorder in contrast to the Class I group. However, the severity of TMD was greater among UCLP group.