English

Cephalometric evaluation of cranio-cervical posture in patient with class II malocclusion. Comparative study of dysfunctional patients and control sample.

Abstract: 

Introduction: the aim of this study was to assess possible changes in the posture of the head, neck and hyoid bone position in patients with Class II malocclusion with and without TMD.

Materials and Methods: The cephalometric tracings of 59 subjects with Class II occlusion were evaluated and compared. The measurements taken into consideration were: C0-C1 distance, C1-C2 distance, cranio-cervical angle and hyoid bone position. The patients studied were divided into two subgroups: subgroup A patients with TMD and subgroup B without TMD. The dysfunctional pathology was diagnosed with the integrated RDC/TMD methodology and the dysfunctions encountered in groups Ia, IIa were considered. The data were subjected to Spearman and Pearson correlation analyses.

Results: the only statistically significant finding was the reduction in the cranio-cervical angle (Pearson R 0.004), this data was significantly greater in the group with TDM.

Conclusions: our results seem to indicate modest correlation between Class II occlusion and abnormalities of the cervical spine. The analysis appears to be more consistent in the TMD group emphasizing the possibility that back rotation of the head on the neck might be related to joint dysfunction.

Authors: 

V. Ferrara

E. Accivile

C. Di Paolo

Introduction: 

The Stomatognathic System (S.S.) is a structural and functional unit that performs basic functions such as swallowing, chewing and talking: this system interacts with the contiguous anatomical structures and systems, participating to other functions such as respiration, digestion, body posture control and balance. This system correlates with the cervical spine and hyoid bone, forming a functional cranio-cervical-mandibular unit 1,2,3. For anatomical and functional reasons, the principles of biomechanics of the head and neck are of great interest in dental (particularly, in the orthognatodontic field) and rehabilitation fields because an altered dento-maxillary condition may involve the cranio-cervical area and vice-versa4,5,6,7,8. Based on a current scientific evidence the relationship between temporomandibular joint, cervical spine and hyoid bone is still unclear in terms of physiological and physiopathological implications9,10,11,12,13,14,15,16,17,18. Visscher et al. 18 (2001); in a study between asymptomatic volunteers and symptomatic patients, cannot find any correlation between cranio-cervical dysfunctions, TMD’s and abnormal head positions18. D'Attilio10 et al. in a 2004 study of female patients with second-class malocclusion aged between 25 and 35 years, found a reduction of physiological cervical curve10. In 2009, Matheus et al. 14 studied a possible correlation between the temporo mandibular joint disc position and cervical spine posture and found a greater reduction in the C0-C1 space in patients with anterior-medial dislocation of the disc, even if they cannot confirm a direct correlation15.  To try a proper assess between the two structures, the data engaged in this study were gathered from cephalometric analysis carried out on specific X-ray imaging19,20,21,22,23. The aim of this study was to evaluate changes in the physiological curve of the cervical spine, head and hyoid bone position in patients with a specific dental alteration as the Class II malocclusion. To strengthen the research field, data were collected on two groups of patients, with and without TMJ dysfunctions (healthy subjects), having in common a dental Class II.

Material and Methods: 

Patients covered by the research were recruited among those who spontaneously contacted the Gnathology Service of Oral and Maxillo Facial Sciences Department of Sapienza University of Rome, and the  Orthodontics and TMJ unit of the George Eastman Hospital of Rome, in the period from September to December 2011. Included in the study were patients with presence of dental Class II who were at least 15-year old and agreed to take part in the study. Excluded from the work were patients with the following features in the studied areas: no teeth in the posterior and lateral area, a history of trauma, previous  orthognatodontic and surgical therapies, structural malformations, systemic diseases. To these basic criteria was added, for the dysfunctional group, the presence of a TMJ disorder. The dysfunctional pathology was diagnosed by a calibrated gnathologist according to the RDC/TMD method, Ia and/or IIa groups of dysfunctions were considered. In light of these considerations, the sample was composed of 59 individuals, 38 females and 22 males, with an average age of 33.65 years. The full sample was divided into two subgroups A and B with and without TMD’s. Group A was collected of 26 patients, 24 females and 2 males, with an average age of 44.69 years. Group B was composed by 33 individuals, 14 females and 19 male, with an average age of 24.33 years. All patients were blinded analyzed by assessing and correlating some linear and angular measures from the cephalometric analysis performed on the lateral skull radiographs. The cephalometric techniques used were chosen in order to study the relationship between the structures interested in the research: jaw and cervical spine, jaw and hyoid bone. Standard orthodontic techniques have been associated with the method proposed by Rocabado22 for the study of the latter variables (FIGURE 1). The parameters considered in the study were the cranio-cervical angle, the C0-C1 distance, the C1-C2 distance and the hyoid triangle. Data taken from the cephalometric analysis were interpreted using basic descriptive statistical analysis, Pearson correlation index for random variables and the nonparametric Spearman ordinary measures to evaluate the association between the different parameters.

Results: 

The data obtained were primarily included in descriptive tables that show base statistics results such as, for example, the number of observations, the ranges of values (minimum and maximum), the mean and the frequency. (The high number of base tables and their irrelevance for the objectives of the study have resulted in their omission.) Tables 1, 2, 3, 4 show the individual measurements taken into account and their frequency. The most significant results and the main summary tables pertaining to the testing of the hypotheses of the study were presented. The results were argued below during the discussion. The data obtained were grouped in intervals of mode (1 for abnormally low, 2 for normal, 3 for abnormally high) to enable detailed comparisons between the various sub-systems and, thus, to verify homogeneity and heterogeneity within the various series. Contingency tables (crosstabs) have then been created in relation to the frequency distribution of the conditional mode ANB, in the presence or absence TDM. 
From all the data analyzes did not emerge particularly significant results: indeed, if the synthesis that the re-coding brings about is particularly useful for the contingency tables, the loss of information and the excessive reduction of data negatively affect the emergence of significant correlations: nevertheless, it is interesting to show the difference between the original values and the recoded values​​, even if when measured with a different correlation coefficient.

Table 1 - Crosstabs with stratification: ANB*ric_C0_C1* disfunc. x TMD

disfunc. x TMD

ANB

 

ric_C0_C1

 

 

 

 

Modality

 

Abnormally (low)

Normal

Abnormally (high)

Total

             

Absent

3

Calculation

1

5

0

6

 

4

Calculation

0

3

2

5

 

5

Calculation

1

9

1

11

 

6

Calculation

1

1

3

5

 

7

Calculation

0

2

1

3

 

9

Calculation

0

3

0

3

 

TOTAL

Calculation

3

23

7

33

 

 

% entro ANB

0,09

0,70

0,21

1,0

 

 

% entro ric_C0_C1

1,0

1,0

1,0

1,0

             

Present

3

Calculation

0

1

0

1

 

4

Calculation

3

2

1

6

 

5

Calculation

4

6

0

10

 

6

Calculation

2

3

1

6

 

7

Calculation

0

1

0

1

 

9

Calculation

0

1

0

1

 

10

Calculation

0

1

0

1

 

TOTAL

Calculation

9

15

2

26

 

 

% in ANB

0,35

0,58

0,08

1,0

 

 

% in ric_C0_C1

1,0

1,0

1,0

1,0

 

Table 2 - Crosstab with stratification. ANB*ric_C1_C2* disfunc. x TMD

disfunc. x TMD

ANB

 

ric_C1_C2

 

 

Modality

 

Abnormal (low)

Normal

Abnormal (high)

Total

             

Absent

3

Calculation

0

6

0

6

 

4

Calculation

2

3

0

5

 

5

Calculation

1

6

4

11

 

6

Calculation

1

3

1

5

 

7

Calculation

0

3

0

3

 

9

Calculation

0

3

0

3

 

TOTAL

Calculation

4

24

5

33

 

 

% in ANB

0,12

0,73

0,15

1,0

 

 

% in ric_C1_C2

1,0

1,0

1,0

1,0

             

Present

3

Calculation

0

1

0

1

 

4

Calculation

2

4

0

6

 

5

Calculation

2

8

0

10

 

6

Calculation

2

3

1

6

 

7

Calculation

0

1

0

1

 

9

Calculation

0

1

0

1

 

10

Calculation

0

1

0

1

 

TOTAL

Calculation

6

19

1

26

 

 

% in ANB

0,23

0,73

0,04

1,0

 

 

% in ric_C1_C2

1,0

1,0

1,0

1,0

 

Table 3 - Crosstabs with stratification. ANB* ric_cranio-cervical angle* disfunc x TMD

disfunc. X TMD

ANB

 

 ric_ cranio-cervical angle

 

 

Modality

 

Abnormal (low)

Normal

Abnormal (high)

Total

             

Absent

3

Calculation

4

2

0

6

 

4

Calculation

1

4

0

5

 

5

Calculation

5

4

2

11

 

6

Calculation

3

2

0

5

 

7

Calculation

3

0

0

3

 

9

Calculation

2

1

0

3

 

TOTAL

Calculation

18

13

2

33

 

 

% in ANB

0,55

0,39

0,06

1,0

 

 

% in ric_ cranio-cervical angle

1,0

1,0

1,0

1,0

             

Present

3

Calculation

0

0

1

1

 

4

Calculation

3

3

0

6

 

5

Calculation

4

6

0

10

 

6

Calculation

3

3

0

6

 

7

Calculation

0

1

0

1

 

9

Calculation

1

0

0

1

 

10

Calculation

1

0

0

1

 

TOTAL

Calculation

12

13

1

26

 

 

% in ANB

0,46

0,50

0,04

1,0

 

 

% in ric_ cranio-cervical angle

1,0

1,0

1,0

1,0

 

Table 4 - Crosstabs with stratification. ANB*ric_hyoid position* disfunc x TMD

disfunc. x  TMD

ANB

 

ric_Hyoid position

 

 

Modality

 

Abnormal (low)

Normal

Total

           

Absent

3

Calculation

4

2

6

 

4

Calculation

1

4

5

 

5

Calculation

5

6

11

 

6

Calculation

3

2

5

 

7

Calculation

1

2

3

 

9

Calculation

1

2

3

 

TOTAL

Calculation

15

18

33

 

 

% entro ANB

0,45

0,55

1,0

 

 

% in ric_Posiz_ioide

1,0

1,0

1,0

           

Present

3

Calculation

0

1

1

 

4

Calculation

3

3

6

 

5

Calculation

5

5

10

 

6

Calculation

5

1

6

 

7

Calculation

1

0

1

 

9

Calculation

0

1

1

 

10

Calculation

0

1

1

 

TOTAL

Calculation

14

12

26

 

 

% entro ANB

0,54

0,46

1,0

 

 

% in ric_Hyoid position

1,0

1,0

1,0

Discussion and Conclusions: 

The basic descriptive analysis of the full sample studied founded that the 35.60% of patients21 presented an ANB angle of 5°, these subjects showed the highest number of abnormal values ​​of all cervical measurements considered. Cranio-cervical angle measurement was out of standard in 38% of patients (32 subjects), 20 of them (62%) were positive to TMD. Crossing the different measurements with ANB values ​​we obtained the following results: 65% of all subjects examined (38 subjects) showed a normal values of C0-C1 space on the vertical plane. C1-C2 space was normal in 73% of patients (43 subjects), this finding showed a decrease in amplitude in 17% (10 subjects) of cases and an enhancement in 10% of them (6 subjects). 

Most significant values were found in the cranio-cervical space, this data appears reduced in 51% of patients (30 subjects), normal in 44% (26 subjects) and increased in 5% of these (3 subjects). The hyoid bone was found to be in a normal limit position in 51% (30 subjects) of the subjects examined and in an outside positive position in 49% of cases (29 subjects). 

Measurements investigated in the study were crossed considering the TMD parameters. Even in this analysis the most interesting data was ANB angle that was increased by 5° in 21 patients (35.59%). The results related to C0-C1 and C1-C2 space in the dysfunctional patients were not significant details. 

Cranio-cervical angle in dysfunctional patients showed some anomalies in 61% (20 subjects) while in  non-dysfunctional sample found out altered in 50% (13 subjects). Disagree with Visscher et al. 18 (2001) this study showed a correlation between the presence of the TMD and the hyperextension of the head on the neck. 

Hyoid bone position was altered in 54% of the dysfunctional patients (14 subjects), this result was similar in 45% of non-dysfunctional subjects (15 of 18). 

Statistical data didn't showed significant correlations between the variables, either in positive either in negative sense. Correlation indexes were always very close to zero, and these proved that distributions were independent from the previous associations. The only strong exception was an inverse relationship between the result of ANB angle and the cranio-cervical angle stratified data in presence of TMD’s. Considering this data, it was possible to infer a negative dependence of the value. Consequently, in about 26 observations, increasing the size of ANB decreases the value of the cranio-cervical angle, and that was true also by the inverse with moderate correlation but without causal link, as mentioned before. The significance was less than 0,005, so the data was verified.

The aim of this study was to evaluate changes in the physiological curve of the cervical spine, head and hyoid bone position in patients with a specific dental alteration as the Class II malocclusion.

The final results of this study suggest that the presence of a class II malocclusion could lead a posterior rotation of the occiput on C1 with a consequent reduction in the functional C0-C1 space, while it did not reveal significant changes in the cervical lordosis and on the hyoid bone position. The largest number of subjects examined, who had a posterior rotation of the head, were positive to the presence of TMD.

Correlation indexes (Spearman index and Pearson index) used in this study did not allow to identify a direction in the relationship between Class II malocclusion and TMD, but it was possible to underline a close relationship between the reduction of the cranio cervical angle and the presence of TMD.

In the light of the significance of the result obtained with this study and given the interest of the clinicians to analyze the physiologic and pathophysiological relationship between these structures, will be useful to examine a greater number of subjects in association with different occlusal anomalies in order to obtain more details and more specific clarifications of these controversial topics.

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