Cheiloscopy: An Early Indicator of Class I & Class II Malocclusion

INTRODUCTION

After all, the mouth is considered as the organ system “where it all begins”¹ . It allows a myriad of possibilities in forensic identification. Apart from teeth, information can also be derived from soft oral and perioral tissue prints. Lips as well as the hard palate are known to have features that can lead to a person’s identification² . Lip prints, fingerprints and palatal rugae are permanent & remain unchanged from birth. The identification of lip patterns is possible as early as sixth week of intrauterine life. Lip groove patterns rarely change, resisting many infections from that moment1.It indicates that the pattern of wrinkles on the lips (lip prints) are analogous to thumb prints³ .

Lip prints are regular lines & fissures which are present in the zone of transition between the inner labial mucosa & the outer skin of human lip. Lip prints are standard pattern formed by wrinkles and grooves on the labial mucosa. Forensic investigation technique that is related with a person’s identification based on lip prints is called Cheiloscopy. This is a method of identification of a person based on characteristic patterning of wrinkles & grooves appearing on the lips or as a science dealing with the lines appearing on red part of the lips² .

Cheiloscopy, acts like a clinical diagnostic aidis analogous to thumbprints and helps us in predicting the prospective malocclusion, as correlation between thumb prints & sagittal malocclusion has already been established³.A Lateral cephalogram is used for diagnosis of sagittal skeletal malocclusion, however Cheiloscopy can help a clinician in reducing patient’s radiation exposure for diagnostic purpose. Many factors can affect the reliability of lateral cephalometric landmark identification, including the nature of cephalometric landmarks, the resolution and quality of digital images, along with individual variability. Lip Print pattern identification is based on already established norms and it can reduce inter- observer errors, which will help in improved diagnosis.

If an interrelationship can be made between sagittal jaw relation and lip prints, it would benefit diagnosing the type of malocclusion and also provide additional information on individual personal identity.

Hence, the purpose of this study was to determine & correlate the lip print patterns in Skeletal Class I & Class II malocclusions, so as to provide valuable information on lip prints to be used as an additional aid for classifying malocclusions.

METHODOLOGY

The study was conducted in the Department of Orthodontics, Bangalore Institute of Dental Sciences & Hospital, with the institutional ethical committee approval. Patients with Skeletal Class I and Class II malocclusion aged 12 years and above were included in the study.

Individuals with known hypersensitivity to lipsticks, cleft lip, lip lesions or any history of facial trauma were excluded from the study. A sample of 160 individuals reporting to Department of Orthodontics and Dentofacial Orthopaedics seeking orthodontic treatment were evaluated for their sagittal skeletal jaw relation after assessment of ANB angular measurements, Wits Appraisal and Beta Angle using Lateral cephalogram. They were categorized (80 patients each) into either:

I. Group A: Class I malocclusion- If ANB angle is between 2 to 4 degrees, Wits appraisal (AO=BO in females & BO is ahead of AO by 1mm in males) and Beta angle is between 27 to 35 degrees.

II. Group B: Class II malocclusion- If ANB angle is greater than 4 degrees, Wits appraisal (AO is ahead of BO) and Beta angle is less than 27 degrees.

Informed consent of the patient was taken prior to the procedure. The lips were cleaned and dried (Fig.6a). A dark coloured lipstick (LAKME enrich satin) was applied onto the lips with a single stroke (Fig. 6b). The subjects were asked to rub both the lips so as to evenly spread the applied lipstick. After about two minutes, a lip impression was made on a strip of transparent cellophane tape (3M Scotch) on the glued portion (Fig. 6c). Lip prints were recorded in rest position by dabbing in the centre first & were pressed comfortably towards the corner of the lips. The cellophane tape was removed & stuck to the white bond paper (Fig. 6d), then labelled which included their name, age and skeletal pattern. This served as a permanent record for lip print analysis & future reference.

Lip print pattern was analysed based on the Suzuki & Tsuchihashi4 classification :

Type I : Clear- cut vertical grooves that run across the entire lips.

Type I’: Similar to type I, but do not cover the entire lip.

Type II : Branched grooves (branching Y-shaped pattern).

Type III : Intersected grooves (criss-cross pattern, transverse grooves).

Type IV : Reticular grooves

Type V : Undetermined (Grooves do not fall into any of the Type 1-4 and cannot be differentiated morphologically)

For determining the pattern of lip prints, it was visualized through a magnifying glass lens (4x magnifications) and the field of observation was restricted to 10mm on each side of the quadrant from the midline (Fig. 7). The lip print patterns were determined by counting highest number of lines in this area having similarity to the Tsuchihashi classification. Chi-square tests & Z-test was utilized to analyse significance of lip prints among both the two sagittal groups. p value was set at ≤ 0.05 (95% confidence interval).

RESULTS

A prospective study was carried out among 160 individuals who were divided into 2 groups with 80 subjects in each group i.e, Skeletal Class I jaw bases & Skeletal Class II jaw bases. The mean age of the study subjects was 22.9 ± 5.2 years in Skeletal Class I & 21.4 ± 5.5 years in Skeletal Class II malocclusion (Table 1, Graph 1).

pattern (41.3%), followed by 18 patients who had Type II/ branched pattern (22.5%), 17 had Type IV/ reticular pattern (21.3%), 6 had Type III/ intersected pattern (7.5%) and 6 had Type V/ undetermined pattern (7.5%). Type I’ lip print/ vertical pattern which do not cover entire lip, was absent among this group. Type I lip print/ vertical pattern was found to be most prevalent in Skeletal Class I malocclusion. (Table 2, Graph 2).

In Skeletal Class II group (n = 80), 35 patients were found to have Type II/ branched pattern (43.8%), followed by 19 patients who had Type I/ vertical pattern (23.8%), 11 had Type IV/ reticular pattern (13.8%), 8 had Type V/ undetermined pattern (10%) & 7 had Type III/ intersected pattern (8.8%). Type I’/ vertical pattern which do not cover the entire lip, was absent among this group. Type II/ branched lip pattern was found to be most prevalent in Skeletal Class II malocclusion. The Chi-square test showed significant difference in the lip patterns in overall subjects having Skeletal Class I and Skeletal Class II jaw bases (P < 0.05) (Table 2, Graph 2).

In overall Skeletal Class I & Skeletal Class II group, among 160 individuals, 53 patients were found to have Type II pattern (33.1%), followed by 52 patients who had Type I pattern (32.5%), 28 had Type IV pattern (17.5%), 14 had Type V pattern (8.8%) & 13 had Type III pattern (8.1%). Type I’ lip pattern was absent among both the groups. The Z‑test (standard normal variant test) for proportion, showed significant difference in the lip patterns in overall subjects having Skeletal Class I and Skeletal Class II jaw bases (P < 0.05). The Z‑test showed a significantly high (P < 0.05) proportion of vertical lip pattern i.e. Type I in subjects having Skeletal Class I as compared to Skeletal Class II jaw bases, while the proportion of branched lip pattern i.e. Type II was significantly high (P < 0.05) in subjects having Skeletal Class II jaw bases. (Table 3, Graph 3)

Chi Square test & Z- test showed significant difference among the lip patterns between skeletal Class I & Skeletal Class II malocclusion (Table 2 & 3).

In our study we have found that there is a statistically significant correlation between the lip prints and skeletal Class I & Class II malocclusions. Further study to assess correlation between lip prints and skeletal Class III malocclusion is indicated.

DISCUSSION

Soft tissues are the most important aspect in orthodontic diagnosis and treatment planning. In cephalometric analysis, measurement of hard tissue structures is mainly concentrated, which are not constantly related to the soft tissue of the face. In modern orthodontic treatment, based on the patient’s overall benefit there is a paradigm shift for achieving ideal occlusion to the more esthetically focused soft tissue paradigm. The orofacial soft tissue profile is mainly determined by the position of the lip and chin, hence they play an important role in diagnosis and treatment planning. In forensic dentistry, along with the use of finger prints, lip prints have also been suggested as an important tool in personal identification of an individual as well as in criminal investigation. Lip prints consist of normal lines and fissures in the form of wrinkles and grooves present in the zone of transition of human lip between the inner labial mucosa and outer skin.¹⁷

In modern orthodontics, extensive research has been done to establish a relationship between the skeletal malocclusions (Class I, II and III) and soft tissue facial morphology. The lip prints are unique to an individual just like the fingerprints and shows strong hereditary pattern. Lip prints are established at a very early period in comparison to sagittal jaw relation and dental relation. Although very few studies are available on lip prints, a landmark study performed by Suzuki et al and Tsuchihashi gave a new dimension to the study of lip prints. They devised standards for classification which formed the foundation of many studies in the future. Tsuchihashi Y investigated lip Prints of 1364 inhabitants of the Metropolitan and rural prefectures of Tokyo, Kanagawa, and Saitama in Japan. It was revealed that Type III was commonest in both sexes followed in order by Types I, II, IV and V.⁴

Kulkarni et al³ compared the gender variation of lip prints and of sagittal skeletal jaw relation as well as related to different lip print patterns with sagittal jaw relations and observed that a combination of Type I, III; I’, III; & II, III were predominant in skeletal Class I, while Type I, II in skeletal Class II and Type I, IV; III, IV in skeletal Class III malocclusion. A significant difference was found in all 3 groups.Similarly, we had also found Type I as the most predominant pattern in skeletal Class I malocclusion & Type II in skeletal Class II malocclusion.

In a study designed by Raghav et al⁵, it was found that in skeletal Class I and Class II groups Type II lip pattern was most prevalent whereas in skeletal Class III group, Type I pattern was most prevalent. Contradicting to this, we found that vertical lip print pattern was more common in skeletal Class I malocclusion in our study, whereas there was a similarity in the results of skeletal Class II malocclusion where branched lip print pattern was more predominant.

In our study, significant differences between the two malocclusions were observed in the Vertical and Branched patterns in accordance with a study conducted by Ponnusamy et al2who assessed the strength of association between lip patterns and skeletal Class I & II malocclusion. Significant differences between the two malocclusions were observed in the Type I and Type II patterns while the Type III, Type IV and Type V patterns showed no difference. This was evident in the females while the males showed differences in the Type I pattern only. Kaushal et al⁶ had conducted a study to explore the possible association of lip prints with Skeletal Class I and Class II malocclusions with varying growth patterns. In Skeletal Class I Normodivergent group and Hypodivergent group, Branched lip pattern was most prevalent whereas in Skeletal Class I Hyperdivergent group Intersected lip pattern was most prevalent. In Skeletal Class II Normodivergent group, Intersected lip pattern was most prevalent. In Skeletal Class II Hypodivergent group, Branched lip pattern was most prevalent whereas in Skeletal Class II Hyperdivergent group, Branched lip pattern and Reticular lip pattern was most prevalent. It was found that Branched lip pattern was most common in the given population with no sexual dimorphism.In contrast, we found that vertical lip print pattern was more common in skeletal Class I malocclusion in our study, whereas there was a similarity in the results of skeletal Class II malocclusion.

Ravindran et al⁷ conducted a study to determine the correlation between various cheiloscopic patterns and permanent molar relationships with completely erupted 2nd permanent molars. The predominant patterns which related to the Angle’s classification were; Type I pattern for class I malocclusion, Type IV pattern for class II malocclusion and presence of Type IV pattern and absence of Type I’ (incomplete vertical) pattern for class III malocclusion.Similarly, the most predominant lip print pattern in Angle’s or skeletal Class I group was the vertical pattern. The most predominant lip print pattern in skeletal Class II group was the branched pattern in our study which was not similar to the lip print pattern found in Angle’s Class II malocclusion in the above study.

Cheiloscopy has been a subject of great interest to most researchers, it being the least invasive, economical and not requiring any complex instrumentation for study purpose. Since lip prints get established before sagittal jaw and dental relationships, lip print assessment may aid the clinical orthodontist to predict the type of malocclusion. Lip prints can be used as an additional diagnostic aid for early detection of skeletal malocclusions. Every orthodontists should be advised to take lip print during their routine record taking procedures.

Thus, Cheiloscopy can act as an early indicator of skeletal malocclusions, but extensive research is needed for the evaluation of lip prints in a larger sample with distinct inherited malocclusions to substantiate the correlation between lip patterns and skeletal malocclusions. There was a significant correlation found between the lip prints and skeletal Class I & Class II malocclusions. Further study to assess correlation between lip prints and skeletal Class III malocclusion is indicated.

• LEGENDS FOR FIGURES / IMAGES :

1)Fig. 1a: Clean & dried lips

2)Fig. 1b: Dark coloured lipstick applied

3)Fig. 1c: Lip impression made on cellophane tape

4)Fig. 1d:Cellophane tape stuck to white bond paper

5)Fig. 2: Field of observation restricted to 10mm on each side of the quadrant from the midline