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EVALUATION OF MANDIBULAR LENGTH IN SUBJECTS WITH CLASS I AND CLASS II SKELETAL PATTERNS USING THE CERVICAL VERTEBRAE MATURATION.

Byline: MUHAMMAD TAYYAB, UMAR HUSSAIN, MUAZZAM ALI, ALI AYUB and FAZAL HADI

ABSTRACT

The prevention, interception, and correction of dentofacial deformities also depend largely on a proper understanding of craniofacial growth and development. For growth modication to be suc- cessful, it is absolutely essential that its start at the right time.

The aim of the present study was to assess mandibular size and cervical vertebrae maturation in subjects of both genders with Class I and Class II malocclusions.

A total 100 patients; 50 males and 50 females having skeletal class I and II malocclusion were included in the study. Mandibular length was measured in millimeter on lateral cephalograms of each patient. Cervical Vertebral Maturation staging was done according to Baccetti et al. The comparison of mandibular length among gender and class of malocclusion was done.

Out of total 100 patients half were males and half females. The age ranged from 8 to 15 years1.97. The commonest age range was 10-13 years. Mandibular lengths were greater in males from females in skeletal class I malocclusion whole no difference in skeletal class II. The longest length was in CS5.. Statistically significant difference was found in mandibular among the gender but not among class of malocclusion.

Key Word: Class II malocclusions, Mandibular length, Cervical Vertebral Maturation staging.

INTRODUCTION

Successful orthodontic diagnosis, treatment plan- ning, and clinical procedures require a thorough under- standing of growth and development.1 The prevention interception, and correction of dentofacial deformities also depend largely on a proper understanding of cra- niofacial growth and development. The craniofacial region is a dynamic biologic continuum that begins in embryonic development and continues through senil- ity,2 and its growth patterns are even more complex.3

Prior knowledge of the amount of growth remaining would be extremely useful for forecasting treatment outcome, taking advantage of growth when necessary and trying to minimize growth when undesirable.4

For growth modication to be successful, it is absolutely essential that its start at the right time. Optimal timing for treatment is different in various malocclusions.5

The classical and most widely used method for skeletal age evaluation which is the highly reliable is Hand-wrist radiograph analysis.6 However, this anal- ysis involved extra radiation exposure for the patients. Currently, the cervical vertebrae investigation method has been increasing in use, since it avoids further ex- posure to ionizing radiation in addition to the routine radiographic records required for an orthodontic treat- ment.7 This method has proved effective in assessing the adolescent growth peak both in body height and mandibular size. The appraisal of the biological aspects of mandibular growth is of fundamental importance in dentofacial orthopedics, especially with regard to the use of functional appliances to correct Class II skeletal discrepancies.8 The evaluation of mandibular skeletal maturation and growth potential in the individual pa- tient provides essential information for the anticipation of treatment results.

It is well known that the growth rate of the human mandible is not constant throughout development. A peak in mandibular growth velocity (pubertal growth spurt) has been described in many previous cephalometric studies.9,10 The intensity, onset, and duration of the pubertal peak in mandibular growth are characterized by great individual variations.8

Class II malocclusion is a commonly observed malocclusion, in many population.11 Despite the sub- stantial prevalence of Class II malocclusion as an orthodontic problem, review of the related literature showed no agreement for growth changes of the man- dible in untreated subjects with Class II malocclusion, when compared with subjects with normal occlusion. Maria and co-workers12 reported the relationship of cervical vertebral maturation and mandibular growth changes by assessing in annual lateral cephalometric radiographs of thirteen Caucasian females from 9 to 15 years of age. Statistically significant increases were found in mandibular length, corpus length and ramus height are associated with specific maturation stages in the cervical vertebrae.

Stahl and colleagues13 carried out a longitudinal study to compare the cra- niofacial growth changes in untreated subjects with Class II Division 1 malocclusion with those in subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development, as defined by a biological indicator of craniofacial growth in subjects with untreated Class II malocclusion was essentially similar to that in untreated subjects with normal occlusion at all developmental intervals, with the exception of significantly smaller increases in man- dibular length (P less than 0.001) at the growth spurt (interval CS3-CS4) and during the overall observation period (intervals CS1-CS6). In contrast, Bisara14 found no difference in mandibular growth in Class II subjects from the deciduous dentition through the permanent dentition.

However, the results in most of these studies were based on longitudinal growth changes related to the subjects' chronologic ages or the dentition stages, which according to many authors, are not reliable predictors.

The aim of the present study was to assess mandib- ular size and cervical vertebrae maturation in subjects of both genders with Class I and class II malocclusions.

METHODOLOGY

This cross-sectional study was undertaken in the Orthodontic Department, Khyber College of Dentist- ry, Peshawar from January 2014 to November 2014. A total 100 cephalometric radiographs were obtained from record of the department. Lateral cephalometric radiograph of each individual was taken with a univer- sal counter balancing type of cephalostat at Radiology Department of Khyber College of Dentistry, Peshawar. Kodak' X-ray films (10 A- 12") were exposed to 70 KVp, 10 mA for an average of 1.8 sec, with a tube to film distance of 6 feet. All lateral cephalograms were placed on illuminator and determination of CVM stages were done by two examiners.

Cervical vertebral maturation staging (CVMS) was evaluated on lateral cephalometric radiographs, according to the method described by Baccetti et al.15 This method has been proved useful in the evaluation of skeletal maturation in a single cephalogram. This method analyzes the morphology of the second (C2), third (C3), and fourth (C4) cervical vertebrae and the patient is classified into one of six stages; CVMS I, CVMS II, CVMS III, CVMS IV, CVMS V and CVMS VI which are given below.

Stage 1 (Initiation): Great amount of pubertal growth expected (80 to 100 %). Inferior borders of C2, C3 and C4 are flat at this stage. The vertebrae are wedge shaped, and the superior vertebral borders are tapered from posterior to anterior.

Stage 2 (Acceleration): Growth acceleration begins at this stage. Significant pubertal growth expected (65% to 85%). Concavities are developing in the inferior borders of C2. The inferior border of C3 and C4 is flat. The bodies of C3 and C4 are trapezoidal in shape.

Stage 3 (Transition): Moderate pubertal growth expected (25% to 65%). Distinct concavities are seen in the inferior borders of C2 and C3. A concavity is be- ginning to develop in the inferior border of C4. Atleast one of C3 or C4 bodies still retains a trapezoidal shape.

Stage 4 (Deceleration): Reduced expectation of pubertal growth (10 to 25%). Distinct concavities are seen in the inferior borders of C2, C3 and C4. The ver- tebral bodies of C3 and C4 are rectangular horizontal in shape.

Stage 5 (Maturation): Final maturation of the vertebrae took place during this stage. Insignificant pubertal growth expected (5 to 10%). More accentuated concavities are seen in the inferior borders of C2, C3 and C4. The bodies of C3 and C4 are square in shape.

Stage 6 (Completion): Pubertal growth complet- ed at this stage (little or no growth expected) Deep concavities are seen in inferior border of C2, C3 and C4. The bodies of C3and C4 are square or are greater in vertical dimension than in horizontal dimension. Sampling was performed according to the convenient sampling method.

The inclusion criteria were:

Pakistani Nationality

Both genders

No systemic disease that could affect general de- velopment like hormonal diseases

Age range from 8 to 15 years

Lateral cephalometric radiographs available with high clarity

No history of trauma or surgery in the neck or dentofacial region.

TABLE 1: AGE DISTRIBUTION OF PATIENTS

Age (years)###Frequency###Percent

###8###4###4.0

###9###10###10.0

###10###13###13.0

###11###14###14.0

###12###17###17.0

###13###14###14.0

###14###20###20.0

###15###8###8.0

###Total###100###100.0

No orthodontic treatment at the time of study

All the participants were divided in Class I or Class II skeletal patterns, according to the ANB angle and WITS appraisal. Class II subjects had the ANB angle greater than 4 and the linear distance between AO and BO (WITS appraisal) greater than 1 mm. Class I subjects had the ANB angle between 0 and 4, with normal distance between AO and BO (1 to 1 mm). The Class I sample consisted of 50 subjects (25 males, 25 females). The Class II sample also consisted of 50 sub- jects (25 males, 25 females). This study was approved by ethical committee of Khyber hospital.

Total mandibular length from Condylion to gna- thion (Co-Gn) was measured on Cephalograms traced by 1 investigator and verified for landmark location and anatomical contours by another. To examine the intra-observer reliability, 20 subjects were reevaluat- ed by both methods. The agreement was assessed by weighted kappa statistics. Kappa was (0.87 0.07) for determination of tooth calcification stages and (0.94 0.09) for cervical maturation. The results revealed that the reproducibility of the diagnosis in our rater was almost perfect. All assessments were performed in a darkened room with a radiographic illuminator to ensure contrast enhancement of the bone images.

TABLE 2: MANDIBULAR LENGTH AMONG SKELETAL CLASS I AND II

###Class of Malocclusion

###Class I###Class II

###Mandibular Length###Mandibular Length

CVM###Gender###Mean###n###Maxi-###Mini-###Mean###n###Maxi-###Mini-

staging###mum###mum###mum###mum

CS1###Male

###Female###77.0011.31###2###85.00###69.00###92.674.51###3###97.00###88.00

CS2###Male###97.332.08###3###99.00###95.00###96.509.90###8###114.00###80.00

###Female###88.0012.29###7###105.00###72.00###88.754.86###8###98.00###84.00

CS3###Male###106.758.54###4###112.00###94.00###101.334.13###6###105.00###96.00

###Female###90.008.53###6###99.00###78.00###88.754.43###4###93.00###84.00

CS4###Male###108.706.93###10###119.00###96.00###96.6712.22###3###110.00###86.00

###Female###92.118.30###9###104.00###76.00###91.255.62###4###96.00###85.00

CS5###Male###113.003.46###3###115.00###109.00###96.000.0###1###96.00###96.00

###Female###121.000.00###1###121.00###121.00###110.179.75###6###119.00###93.00

TABLE 3: COMPARISON OF MANDIBULAR LENGTH BY GENDER AND CLASS OF MALOCCLUSION

Test values###Mandibular length###Test values###mandibular length among

###among gender###malocclusion group

Chi-Squareb###9.285###Chi-Squarec###2.21

Df###1###Df###1

Asymp. Sig.###0.002###Asymp. Sig.###0.137

RESULTS

Out of total 100 patients 50(50%) were males and 50(50%) females. The age ranged from 8 to 15 years 1.97. The common age rang was 10-13 years (Table 1) Mandibular lengths were greater in males from females in skeletal class I malocclusion whole no dif- ference in skeletal class II. The longest length was in CS5. (Table 2). Satistically significant difference was found in mandibular length amongst the gender but not amongst various classes of malocclusion.(Table 3).

DISCUSSION

Serial headlms have been used by many research- ers to evaluate human mandibular growth, with the analysis typically based on regional superimposition of serial lateral cephalograms on stable anatomical structures. The sequential growth and remodeling of the mandible in children has been of interest due to its important role in orthodontic treatment.16 An under- standing of the normal growth processes enables us to differentiate the effects of orthodontic and orthopedic treatments from the changes occurring during normal growth and development.17

In orthodontics and dentofacial orthopedics, each patient's skeletal maturation period is an important fac- tor to be considered in order to better take advantage of his/her growth potential. In recent years, many authors have supported the efficacy of the cervical vertebrae analysis to assess skeletal age, which would represent a valid instrument to calculate the speed of growth and skeletal maturation.18-21 in the current study, we use CVM for evaluation of mandibular length in skeletal class I and II patients.

In the current study mandibular length showing no statistically difference between the skeletal class I and II with p-value= 0.137. Stahl et al22 compared the longitudinal craniofacial growth changes in untreat- ed subjects with Class II malocclusion with those in subjects with normal occlusion from the prepubertal through the postpubertal stages of development, as defined by the cervical vertebrae maturation method. These authors found that the deficiency in mandibular growth in Class II subjects is significant not only at the growth spurt, but that it is also maintained at a postpubertal observation. The present study is cross-sec- tional as opposed to Stahl et al22, whose result are not in accordance with the present study. Ethnic factors, small sample size, and cross-sectional study design may be responsible for variation in the results.

Other factors which are responsible for class II other than mandibular length; are vertical rotation of mandible23 and position of condyle in gleniod fossa.24

Sexual dimorphism was found in skeletal class I and not in skeletal class II. Generoso et al25 conducted a study to Evaluation of mandibular length in subjects with Class I and Class II skeletal patterns using the cervical vertebrae maturation on 80 skeletal class I and 80 skeletal class II with equal males and female in each malocclusion group. The mandibular length differed between skeletal patterns only at the earlier stages of development. In the Class I pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS4 and CS5, whereas in the Class II pattern, the mandibular lengths of boys were greater than those of girls at stages CS2, CS3 and CS4. The present results indicate a sexual dimorphism in the mandibular length at almost all stages of bone maturation, in exception of the CS5 stage in Class II. In skeletal class I the current results are supported by Generoso et al but show variation in skeletal class II.

Bishara et al26 in a study compared longitudinally the changes that occur in dentofacial structures from the deciduous to the permanent dentitions in untreat- ed Class II division 1 and normal individuals. Sixty five subjects at three stages of development: at the completion of the deciduous dentition, after the first permanent molars had erupted completely, and after the permanent dentition had erupted completely (third molars excluded) were assessed. On a cross-sectional basis, only mandibular length (Ar-Pog) differed sig- nificantly in the two groups, and then only during the earlier stages of development; by the later stage, the difference was not significant, indicating that some "catch up" growth may occur in Class II individuals. Longitudinal comparisons of the curve profiles, i.e., growth trends between Class II division 1 and normal subjects, indicated that there were no significant dif- ferences between the two groups except in upper lip protrusion.

Comparisons of the total change from the deciduous to the permanent dentition indicated the presence of a number of significant differences between Class II division 1 and normal subjects, including larger magnitude of maxillary and mandibular lengths in the normal group and greater skeletal and soft tissue con- vexities in the Class II group.no difference was found in between class I and class II patients in the current study.

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Publication:Pakistan Oral and Dental Journal
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Geographic Code:9PAKI
Date:Mar 31, 2015
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