Soft Tissue Cephalometric Measurements Among Malaysian Malays and Chinese

Objective: To obtain the standardized values of individuals of Malaysian Malay and Chinese for further relevant research, such as treatment planning and aesthetical considerations.  Material and Methods: In this retrospective study, 440 (305 were Malays and 135 were Chinese) standardized lateral cephalometric radiographs of orthodontic patients selected through simple random sampling are profiled using Holdaway’s analysis. The independent t-test was used to assess the disparities in race and gender. The significant level was p<0.05 .  Results: Significant differences were found between the Malays and Chinese in their skeletal profile convexity, superior sulcus depth, inferior sulcus to the H line and nose prominence. Between Malay females and males, there are significant differences in superior sulcus depth, soft tissue subnasale to H line, basic upper lip thickness, upper lip thickness and nose prominence. Between Chinese males and females, there were differences in their skeletal profile convexity, upper lip to H line, basic upper lip thickness and upper lip thickness .  Conclusion: The findings demonstrated the difference between standardized norms and the unique profiles of Malaysian Malays and Chinese. There are significant gender disparities in the soft tissue cephalometric measurements among Malaysian Malay and Chinese subjects.


Introduction
A lateral cephalometric radiograph (LCR) is a standardized, reproducible radiograph used primarily for orthodontic diagnosis and treatment planning. Lateral cephalometry analysis is well known and accepted throughout the dental profession as it is a reliable and reproducible diagnostic method that has allowed orthodontists to formulate treatment plans, measure changes in jaw positions and teeth due to treatment and growth [1].
The objective of modern orthodontics is a maximal comprehensive diagnosis; in which soft tissue analysis is included, because orthodontic treatment give a significant effect on the soft tissue profile [2]. We can thus see the importance of soft tissue analysis towards orthodontic treatment and this fact has been acknowledged by the vast influx of research in this area by several authors who compared the soft tissue cephalometric values of subjects of Korean descent to European American norms [3]. They noted that "orthodontic diagnosis typically includes comparing a patient's cephalometric measurements to standard values. Lateral cephalometric norms, however, may be specific to an ethnic group and cannot always be applied to other ethnic types". This has been verified by other researchers who have sought to compare the soft tissue values of different ethnic groups with the established "norms" which are based on profiles of individuals of European American descent evaluating adults of Saudi Arabian descent based on Holdaways analysis [4], Japanese [5], and the Anatolian Turkish ethnic group [6]. All researchers concur that many of the norms are significantly different from ethnic group to ethnic group, and that these differences play a major role in orthodontic treatment planning.
In this study, we assess the soft tissue cephalometric measurements among the ethnic groups of Malaysian Malays and Chinese using Holdaway's analysis. Related research in this area has been done such as the changes of lip morphology related to different skeletal indices for the same ethnic groups. However, no research in Malaysia has been done for Holdaway's analysis for Malaysian Malays and Chinese. This study will compare their satisfaction of patients who received posterior dental implants in relation to their muscle activity done by electromyography and also clinical findings. Besides academic curiosity, this research will help shed light on the deviations of soft tissue parameter values, which may aid further relevant research in this area, such as orthodontic treatment planning and aesthetical considerations for Malaysian Malays and Chinese.
Based on these, the aim of our study was to formulate cephalometric soft tissue norms of Malaysian Malays and Chinese using Holdaway's linear and angular measurements and also to compare and investigate the differences between the soft tissue profile of Malaysian Malays and Chinese.

Study Design and Sample
This was a retrospective study involving the collection and analysis of lateral cephalometric radiographs of volunteers. The samples were from students of Universiti Sains Malaysia Kampus Kesihatan (USMKK) who were of Malaysian Malay or Chinese descent who fulfilled the inclusion criteria. The samples collection was based on the following criteria: 1) Subjects of whom both parents are of either fully Malaysian Chinese descent / fully Malaysian Malay descent; 2) Those with normal occlusion as based on the British Standards Institute; i.e., an occlusion satisfying the requirements of function and aesthetics with a Class I incisor relationship (lower incisor edges occludes with or lie immediately below the cingulum plateau of the upper central incisors) [7]; 3) Subjects that had no previous orthodontic treatment; 4) Full dentition from second molar to second molar; 5) No skeletal abnormality; 6) Little or no incisor crowding, and 7) Balanced facial skeletal profile.
The radiographs were traced by one investigator. Each group was profiled using Holdaway's analysis, both linear and angular measurements. Figure 1 showed the reference lines being used in Holdway's analysis and Figure 2 showed a cephalometric tracing close-up illustrating the linear and angular measurements being used.

Control of Error
The reliability was analyzed by calculating the Dalhberg's formula: ME = √Σ(x1-x2)2/2n. To determine the difference between 2 measurements made at least a month apart. In which x1 was the first measurement, x2 was the second measurement and n the number of repeated records [8]. Twenty randomly selected lateral cephalometric radiographs will be retraced and re-measured to calculate the method error [8].

Statistical Analysis
Descriptive statistics of the measured parameters (two angular and nine linear) were obtained for all lateral cephalometric radiographs. For each variable, calculations were made to obtain the mean, mean difference and standard deviation. The data were verified and analyzed statistically using IBM SPSS, Statistics Version 20.0, with confidence level set at 5% (p<0.05) to test for significance among the sexes and race. Sexual and racial dimorphisms were evaluated by the t-test.
To assess whether there was a significant level of error during data collection, 44 lateral cephalometric radiographs (10 percent of the entire body of data) were selected at random and repeated one month apart. The combined error was considered to be within the acceptable limit, which was less than 0.42 mm for linear measurements and 0.63 degrees for angular measurements [8]. Table 1 shows the difference of linear and angular measurements for Holdaway's analysis between Malaysian Malays and Chinese, as well as a comparison to Holdaway's norms.  Tables 2 and Table 3 respectively shows the differences of linear and angular measurements for

Results
Holdaway's analysis between the genders for both the Malay and Chinese ethnic groups, respectively.   Table 4 shows a simple summary of significant differences for all comparisons done in this study.

Discussion
The data that we retrieved from the 440 traced lateral cephalometric radiographs were analyzed in 3 ways: First, we compared the general means of Malaysian Malays and Chinese to each other, and then we compared the inter-gender disparities for each ethnic group.
Out of 11 parameters measured according to Holdaway's analysis, we found that the soft tissue profile of Malaysian Malays and Chinese had significant differences in four parameters, with the other seven showing the differences to be insignificant. Therefore, we can conclude that the facial soft tissue profiles of Malaysian Malays and Chinese are mildly similar. Malays had a slightly concave facial profile compared to Chinese, whose facial profile was slightly convex. Malays also generally had a comparatively deeper upper lip sulcus depth, falling just outside of Holdaway's normal range for Caucasian adults. Malays also had more prominent noses compared to Chinese and exhibited a greater distance from the inferior sulcus to H-line. The rest of the values, however, showed insignificance in differences.
For the gender disparities, the finding that the H angle is greater in men agrees with the results of many researchers. However, it has been suggested that there were no sex differences in H angle measurements [9]. Our findings were similar to their results, in that we found no statistically significant differences between men and women for both Malaysian Malays and Chinese. This finding was also reported by previous authors in a study involving the Anatolian Turkish population [6]. When we compare the data across both ethnic groups, there are certain similarities that we can observe, namely that the UL-A and UL-V measurements are greater for males compared to females, indicating that for Malaysian Malays and Chinese, generally males have a thicker upper lip compared to their female counterparts. Once again, our findings concur with some authors [4,6]  Chinese noted that while the amount of lip separation was similar in both sexes, the lips were more protrusive in the females compared to males [10] and these findings coincide with those described by other authors [11,12]. It has been reported that the protrusion could appear to be exaggerated due to the reduced prominence of the nose and chin in Chinese females compared to males [12]. On the other hand, some authors emphasize that this apparent protrusion was due to the thickness of the soft tissue profile and alveolar prognathism [11]. However, in this study, we found no significant difference in nose prominence between Chinese males and females, results that are different from those found in other studies [10,12]. This study also found the length of the nose of the males and females to be largely similar.
Studies done to detail the cephalometric norms for Malaysian Malays are few and far between.
Pioneering research comparing the norms for Malaysian Malays to Glasgow Caucasian adults, with a focus largely on hard tissue parameters, has been developed [13]. Subsequent research profiled Malaysian Malays according to Steiner's analysis [14]. Although the research was mainly focused on hard tissue profiling, it is interesting to note that they found that when compared to Caucasians, Malaysian Malays had more protrusive upper and lower lips, with a less prominent chin and this concurred with previous findings [13]. We hope that more research can be done in this area of profiling the soft tissue cephalometric norms of the local ethnic groups of Malaysia as it is just as important as hard tissue profiling for orthodontic diagnosis and treatment planning. As of now, the amount of research into soft tissue cephalometric norms for Malaysian ethnic groups is lacking, a fact we hope can be rectified in the future as soft tissue profiling becomes more and more recognized.

Conclusion
There are significant differences in the soft tissue cephalometric measurements between Malaysian Malays and Chinese and between Malay males and females. There are significant differences in the soft tissue cephalometric measurements and between Chinese males and females.

Financial Support
None.