Murtazaev S.S.

Tashkent State Dental Institute

ANALYSIS OF СEPHALOGRAMS BY TWEED MERRIFIELD METHOD IN REPRESENTATIVES OF THE UZBEK POPULATION.

Objective: To conduct cephalometric analysis of the representatives of the Uzbek population by Tweed Merrifield method.

Material and methods: A dental examination of 96 ethnic Uzbeks, including 49 women and 47 men, with the generated normal bite. Cephalometric analysis was carried out by Tweed Merrifield method.

Results: The study found significant differences in parameters such as: FMA, Total Chin, Post Face Ht, Ant Face Ht, Index.

Conclusion: The data limited the usefulness of international standards, which are recognized ethnic and other features of the surveyed groups.

Keywords: Normal bite, Tweed Merrifield analysis, lateral cephalograms, ethnicity rate.

Introduction.

We know the value of cephalometry, morphometry of the face and jaw models that facilitate the diagnosis, planning orthodontic, surgical treatment and assessment of the immediate and remote of the results [1].

Cephalometric standards of people with ideal occlusion have been developed by many researchers abroad and recommended by them as standards in the analysis of disease [3,5]. Unfortunately, most of the work is not given the nature and character of the material, based on which the derived average and therefore the possibility of a statistical comparison our data with other countries is limited. In this case, for the average data (standards) are often used mixed performance-ethnic group of people. However, the indicators developed by the standards of foreign authors need to check their acceptability to the people of our geographic area. Using these average values will hardly help in the diagnostics of dentoalveolar anomalies in the Uzbek population. For this reason, it is advisable to examine a group of Uzbek people with the generated normal (orthognatic) bite. This would allow us to receive interest for the value of the national group.

Objective: To conduct a cephalometric analysis in the representatives of the Uzbek population by the Tweed-Merrifield method.

Material and Methods:

The study included 96 ethnic Uzbeks (49 women and 47 men) aged from 17 to 25 years with a developed normal bite. The object of the research was 96 cephalograms of young Uzbek volunteers of both genders. Cephalometric survey was carried out using a X-ray machines Kodak company Morita and (USA, Japan). Cephalometric analysis provided by Tweed-Merrifiel method [6,7,8,9]. All subjects tested were born and lived in the territory of the Republic of Uzbekistan; all of them grew up and were formed in the same geo climatic conditions. All measurements were performed in the phototechnical laboratory of the orthodontics department, Rostock University (Germany).

The measurements were performed manually and with the help of a special computer analysis program 3.2.5 package FR win professional (Computer Konkret®, Falkenstein, Germany).We determined ethnic heritage by surveying and identifying representatives’ genealogy for four generations: 1).The proband; 2).The proband’s mother and father; 3).The proband’s grandmother and grandfather from the mother’s and father’s line; 4).The proband’s great grandmother and great grandfather from the mother’s and father’s line. Research included the probands whose ancestors belonged to the same ethnic group.

Observable groups included people selected according to the following criteria: normally functioning tooth-jaw-facial system and masticatory efficiency and the decayed, missing, and filled teeth (DMFT) index. Absence of any tooth was not acceptable. All examined did not have any morphological and functional deviations from accepted standards and were characterized by absence of clinical pathologies. None of them had previously received orthodontic treatment. As for social status, all of them were students of different institutes and universities of Tashkent city. Received results were processed by the method of variation statistics on computer IBM PC Pentium-IV with use of Microsoft Excel programs for Windows 2010. All values are presented as mean (М) SEM (m). For data with normal distribution, inter-group comparisons were performed using Student’s t-test. A value of P<0.05, P<0.001 was considered statistically significant.

Results.

The results of cephalometric analysis of the Uzbek population on the Tweed to the method presented in the table. As it can be seen from the table, in the study of the average values of the inclination of the lower central incisor in relation to the Frankfurt horizontal mandibular plane no significant differences were found between men and women. However, women have a significantly larger angle of the mandible inclination towards Frankfurt horizontally FMA. The difference of the absolute size of the head and the individual organs of the maxillofacial area in men and women has been noticed during the inspection study, when looking through their cephalogram, as well as the comparison of jaws models. As a rule, men had a large skull, conspicuous large mass of soft tissue covering the front of the skeleton, and dental arch in males were larger. As expected, the statistical processing of the data revealed a significant difference with reliable basic linear measurements in men and women Total Chin, Post Face Ht and Ant Face Ht. Table

Results by Tweed-Merrifield cephalometric analysis method of the representatives of the Uzbek population

Gender	Male			Female
Name	M	m	SD	M	m	SD	P
IMPA (°)	96,2	1,01	6,89	95,9	1,02	7,1	P>0,05
FMIA (°)	61,4	1,16	7,96	59,0	1,01	7,1	P>0,05
FMA (°)	22,3	0,84	5,76	25,2	0,71	5,0	P<0,05
Occ Plane	9,0	0,5	3,44	10,2	0,46	3,2	P>0,05
Z Angle	76,4	1,23	8,43	75,7	1,01	7,1	P>0,05
Total Chin	15,6	0,38	2,58	13,9	0,24	1,7	P<0,05
Post Face Ht	54,9	0,74	5,06	48,5	0,56	3,9	P<0,05
Ant Face Ht	67,0	0,69	4,73	61,4	0,50	3,5	P<0,05
Index	82,8	1,24	8,53	79,2	0,99	7,0	P<0,05

Discussion

The Tweed method (1954) is based on the use of the diagnostic facial triangle that form the Frankfurt horizontal (FH), the base plane of the mandible (the MP) and the longitudinal axis of the lower incisors (LI). According to the proposed tweed angle data obtained at the intersection of Frankfurt horizontal plane and the lower base jaw, is 25° (1); angle obtained at the intersection of the longitudinal axis of the lower incisors and Frankfurt horizontal is 65° (2); angle obtained at the intersection of the longitudinal axis of the lower incisors and the lower jaw base plane, equal to 90 ° (3). The author notes that the aesthetics of the person depends on a degree of inclination of the longitudinal axis of the lower incisors to the Frankfurt horizontal (2). If this angle is 65 °, the person has a perfect harmony. When treating any malocclusion in order to improve the appearance of the patient is necessary to fix the axial inclination of the teeth so that the angle approaching 65°.

Derived Tweed averages are widely used as a standard in many countries around the world, especially in America. Unfortunately, we could not find a detailed description of the nature and characteristics of the statistical material so Tweed statistical comparison impossible. However, according to the average data, our group studied is characterized by the same features that are listed in Tweed analysis, but they are less pronounced. Our group has smaller FMA angle sizes (an average of 2°), and FMIA (an average of 5°). The lower incisors show greater vestibular inclination relative to the mandibular plane to 6°(Figure).

Fig. - Tweed’s Facial Triangle

Our data support the idea that the cephalometric analyzes are often based on a comparison of the data obtained from the survey of the particular patient (patient group), with the average values in this population (e.g. European). Therefore, in recent decades in the foreign literature it appeared a number of works devoted to the study of morphometric parameters and cephalometric norms for the individual ethnic groups and nationalities that have their own characteristics [2, 4].

Based on cephalogram analysis from ethnic Uzbeks with orthognatic bite and formed dental arches, we obtained average cephalometric indicators of angular and linear measurements.

The data serve as a basis for judging the deviation norm in the facial skeleton and, in particular, in its gnathic parts at ethnic Uzbeks. These parameters will be the norm in the criteria for cephalometric studies for the treatment of patients with dentoalveolar anomalies. This facilitates the clinical diagnosis, preparation of management plan for orthodontic, surgical treatment and assessment of their immediate and long-term results.

Conclusions:

1. Installed by us average data for Tweed method Merrifield Men and women need to be considered when diagnosing and planning treatment of patients with dentoalveolar anomalies.

2. Our surveyed group has much greater vestibular inclination of the lower incisors to the mandibular plane.

3. All of the above limits the usefulness of international standards, which seems to reflect the ethnic and other features of the surveyed groups.

References

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