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جلد 35 شماره 1 صفحات 31-40 برگشت به فهرست نسخه ها
Localization of Impacted Maxillary Canine Teeth: A Comparison between Panoramic and Buccal Object Rule in Intraoral Radiography
چکیده:   (285 مشاهده)

Objectives: This study aimed to compare the efficacy of panoramic radiography and the buccal object rule in intraoral periapical radiography for localization of impacted maxillary canine teeth.

Methods: A total of 20 panoramic radiographs depicting 28 displaced maxillary canines were evaluated. The ratio of the mesiodistal width of the impacted canine to the mesiodistal width of the ipsilateral central incisor was calculated and referred to as the canine-incisor index (CII). The height of the crown of each displaced canine was classified in vertical plane relative to the adjacent incisor as apical, middle or coronal. Position of impacted maxillary canines was also determined on two periapical radiographs using the buccal object rule. Surgical exposure and direct observation of impacted teeth were later performed and served as the gold standard. The data were analyzed using SPSS and t-test.

Results: There was an overlap in the CII range of the buccally (0.78-1.48) and palatally (1.15-1.75) positioned impacted canines. When considering the height factor in the middle and coronal zones, a significant difference was noted between the CII of buccally (0.78-1.1) and palatally (1.15-1.75) positioned teeth enabling determination of their buccolingual orientation (P<0.05).

Conclusion: For the impacted maxillary canines located in the middle and coronal zones (90% of cases), the CII of 1.15 and higher represents palatal impaction while the CII smaller than 1.15 represents buccal impaction.

متن کامل [PDF 196 kb]   (97 دریافت)    
نوع مطالعه: پژوهشي | موضوع مقاله: تخصصي
دریافت: ۱۳۹۵/۲/۱۵ | پذیرش: ۱۳۹۵/۱۱/۳ | انتشار: ۱۳۹۶/۴/۱۲

Localization of Impacted Maxillary Canine Teeth: A Comparison between Panoramic and Buccal Object Rule in Intraoral Radiography

Sima NikneshanMehran Hosseinzadeh Mehrdad Dehghanpour barooj3 Mahtab Kheirkhahi*4

1Dept. of Oral & Maxillofacial Radiology, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran

2General practitioner, Tehran, Iran

3Dept. of Oral & Maxillofacial Surgery, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran

4Dept. of Oral & Maxillofacial Radiology, Dental School, Semnan University of Medical Sciences, Semnan,Iran

*Corresponding Author:

Kheirkhahi M.

E-mail: mahtabkh2000@yahoo.com

Received: 04.05.2016

Accepted: 22.01.2017

ObjectivesThis study aimed to compare the efficacy of panoramic radiography and the buccal object rule in intraoral periapical radiography for localization of impacted maxillary canine teeth.

Methods: A total of 20 panoramic radiographs depicting 28 displaced maxillary canines were evaluated. The ratio of the mesiodistal width of the impacted canine to the mesiodistal width of the ipsilateral central incisor was calculated and referred to as the canine-incisor index (CII). The height of the crown of each displaced canine was classified in vertical plane relative to the adjacent incisor as apical, middle or coronal. Position of impacted maxillary canines was also determined on two periapical radiographs using the buccal object rule. Surgical exposure and direct observation of impacted teeth were later performed and served as the gold standard. The data were analyzed using SPSS and t-test.

Results: There was an overlap in the CII range of the buccally (0.78-1.48) and palatally (1.15-1.75) positioned impacted canines. When considering the height factor in the middle and coronal zones, a significant difference was noted between the CII of buccally (0.78-1.1) and palatally (1.15-1.75) positioned teeth enabling determination of their buccolingual orientation (P<0.05).

Conclusion: For the impacted maxillary canines located in the middle and coronal zones (90% of cases), the CII of 1.15 and higher represents palatal impaction while the CII smaller than 1.15 represents buccal impaction.

Key Words: Cuspid; Tooth, Impacted; Radiography, Panoramic

How to cite:

Nikneshan S, Hosseinzadeh M, Dehghanpour barooj M, Kheirkhahi M. Localization of Impacted Maxillary Canine Teeth: A Comparison between Panoramic and Buccal Object Rule in Intraoral Radiography. J Dent Sch 2017; 35(1): 31-40.

Introduction

Maxillary canine impaction is not rare and has a prevalence of 1-3% in different populations (1). Although canine impaction may not be problematic, complications such as cystic changes of the follicles of impacted teeth, neoplastic transformation, crowding, infection and caries in the adjacent teeth may occur. Also, this condition may sometimes result in dull pain of unknown origin (2).

According to Becker et al, (3) the prevalence of canine impaction in subjects with a missing lateral incisor is 2.4 times the rate in individuals with normal dentition. Irrespective of the causes of maxillary canine impaction, the first step in treatment of patients is accurate localization of the impacted canine three-dimensionally. Generally, two methods are available for localization of impacted canines: Clinical assessment and radiographic assessment. Clinical assessment by use of the following clinical symptoms can help in detection and localization of impacted canines: (I) Delay in eruption of permanent canine tooth or prolonged retention of the primary canine beyond the age of 14–15 years; (II) absence of normal canine bulge in the palatal surface; (III)  presence of canine bulge in the palatal surface; and (IV) displacement, distal inclination or delay in eruption of lateral incisor .According to Ericson and Kurol (4) canine bulge at a young age is not a prognostic/diagnostic indicator of impaction and must be accompanied by radiographic assessment. Since clinical symptoms may be rarely seen in patients with an impacted canine, in many cases the clinicians must only rely on radiographic assessment.

Radiographic assessment can be done using the following four techniques. The same lingual opposite buccal (SLOB) rule also known as the Clark’s rule, buccal object rule or the parallax method, which is based on two periapical radiographs captured at different angles (5). In 1952, Richards (6) changed the tube angle in the vertical plane. Keur (7) suggested two occlusal films instead of two periapical films (the occlusal method); however, this method was also based on the Clark’s rule. In 1987, Keur (7) combined an occlusal radiograph with a panoramic radiograph using the vertical tube shift (VTS) method (combined method). Panoramic radiography is also routinely prescribed for patients with impacted teeth. This method only increases the radiation dose to the level of an occlusal radiograph, which is an advantage (7,8).

Panoramic radiography technique is based on a main rule in radiography; that is, an object closer to the radiographic film and farther from the X ray tube has a smaller image than an object farther from the film and closer to the X ray tube. Thus, if the impacted canine is closer to the X ray tube than the contralateral canine, the image of the impacted tooth would be larger than that of the contralateral tooth on a panoramic radiograph. Unfortunately, this method has low accuracy and reliability (9,10). Panoramic radiography is routinely prescribed for orthodontic patients and thus, finding an accurate method to enhance the localization of impacted canines using panoramic radiography would be cost effective and eliminate the need for additional radiographs. Also, panoramic radiographs show a wide view of anatomical structures and thus can visualize the relationship of the impacted canine with the neighboring anatomical structures.

Computed tomography is among the most accurate techniques for localization of impacted teeth. However, despite high accuracy, high patient radiation dose associated with this technique minimizes its application for this purpose. The objective of this study was to find a method to increase the accuracy and reliability of panoramic radiography for precise localization of impacted canines.

Methods

This analytical qualitative study was conducted on impacted canines. Data regarding the impacted canines, ipsilateral central incisor and the contralateral canine were collected. Type of impaction (position of impacted canine in the jawbone) was also evaluated. All panoramic and periapical radiographs taken were analyzed using the SLOB method and the respective variables were recorded. Demographic information of patients was also recorded via an interview. The result of direct observation of the tooth during its surgical extraction was also noted. Patients with a clear bulge in the buccal or palatal surface at the site of impaction were excluded. Subjects presenting to the orthodontics and radiology departments of Shahid Beheshti University, School of Dentistry were selected using convenience sampling. Study subjects included 22 patients (13 males and 9 females) presenting to orthodontics and radiology departments of Shahid Beheshti University, School of Dentistry for treatment of unilateral or bilateral canine impaction. All patients had one panoramic and two periapical radiographs (suitable for the SLOB method). All panoramic radiographs had been taken using Planmeca panoramic imaging system (Planmeca, Helsinki, Finland). Intraoral radiographs had been taken with Planmeca intraoral dental X ray unit and processed by a fully automated processor (Velopex, London, England). Patients under orthodontic treatment whose periapical radiographs had been interpreted by the attending orthodontists underwent surgical extraction of the impacted teeth. A flap was elevated and the impacted tooth was directly visualized. Patients presenting to the radiology department underwent the same procedure (2 patients).

Radiographic analysis of panoramic radiographs of patients:

  1. The maximum mesiodistal width of canine tooth along a perpendicular line relative to the long axis of the impacted tooth was measured (Figure 1).

Figure 1- Maximum mesiodistal width of canine tooth along a perpendicular line relative to the long axis of the impacted tooth

  1. The maximum mesiodistal width of the ipsilateral central incisor along a perpendicular line relative to the long axis of the central incisor was measured (Figure 1).
  2. In patients with the contralateral canine tooth in its correct position, the largest mesiodistal width of this tooth was also measured as described above (Figure 1).
  3. The crown height of the impacted canine was assessed relative to the crown height of the ipsilateral central incisor. The ipsilateral central incisor was vertically divided into three zones of coronal third, middle third and apical third. Then, the crown height of the impacted canine was estimated accordingly (Figure 2).

Figure 2- The crown height of the impacted canine was estimated

  1. Mesiodistal width of the maxillary first molars of both sides was also measured.

The ratio of the mesiodistal width of the impacted canine to the mesiodistal width of the ipsilateral central incisor was calculated and referred to as the CII.

In patients with unilaterally impacted canine and the contralateral canine in its correct position, the ratio of the mesiodistal width of the impacted canine to the mesiodistal width of the contralateral canine was calculated and considered as the control group (canine-canine index or CCI).

Using the SLOB rule, buccolingual position of the impacted canine was determined on periapical radiographs again and compared with initial diagnosis. Related data were recorded in separate datasheets for each patient. In case of absence of clinical symptoms such as swelling or buccal or palatal bulge in an interview with patients, the data form was completed. 

Mesiodistal width of the maxillary first molars of both sides was measured by a caliper and the panoramic radiographs of cases with more than 5% difference were excluded from the study (2 cases) because it indicated excessive magnification of the image and since this study was based on magnification of impacted canines, the radiographs with excessive magnification would interfere with accurate diagnosis.

Localization of impacted canine using the panoramic radiography method alone is based on magnification of impacted canine on the radiographs. In other words, if the impacted tooth was palatally positioned, the tooth would have a larger image than a normally positioned tooth with the X ray tube behind and the radiographic film in front of the patient.

Also, if we assume that the ratio of the mesiodistal width of a normal canine tooth relative to the mesiodistal width of the ipsilateral central incisor is relatively constant (with a specific range), we expect this ratio to increase in the image as well for a palatally positioned tooth (since it would have a magnified image) and vice versa.

Data including the mesiodistal width of the impacted canine on a panoramic radiograph, mesiodistal width of the ipsilateral central incisor on a panoramic radiograph, mesiodistal width of the contralateral normal canine (if present), mesiodistal width of the maxillary first molars of both sides on panoramic radiographs and clinically measured mesiodistal width of the maxillary first molars of both sides were collected. For the purpose of data analysis, the crown height of the impacted canine was measured and categorized as apical, middle or coronal relative to the crown height of the ipsilateral central incisor. These data along with the CCI and CII values were analyzed using SPSS via t-test. Level of significance was set at P<0.05.

Results

Of 20 patients, eight had bilaterally impacted canines (40%); out of which, four had palatally positioned bilateral impacted canines (20%) and three had buccally positioned bilateral impacted canines (15%); in one patient, one impacted canine was buccally positioned while the other one was palatally positioned (5%). Table 1 presents the frequency distribution of the vertical orientation of buccally positioned canines. Table 2 shows the frequency distribution of the vertical orientation of palatally positioned canines.

Table 1- Frequency distribution of the vertical orientation of buccally positioned canines

Vertical orientation

N

Total (%)

Buccally positioned (%)

Apical

2

7.1

18.1

Middle

2

7.1

18.1

Coronal

7

25

63.6

Total

11

39.2

100

Table 2- Frequency distribution of the vertical orientation of palatally positioned canines

Vertical orientation

N

Total (%)

Buccally positioned (%)

Apical

1

3.5

5.8

Middle

13

46.4

76.4

Coronal

3

10.7

17.6

Total

17

60.8

100

General assessment of samples irrespective of their vertical orientation relative to the ipsilateral central incisor with regard to the CII revealed that the CII varied from 1.15 to 1.75 for the palatally positioned impacted canines and from 0.78 to 1.48 for the buccally positioned impacted canines. An overlap existed between the above-mentioned results, which makes accurate localization of impacted canines difficult. Thus, it is not possible to rely on these figures for this purpose.However, assessment of these results based on the crown height of the impacted canine At the apical zone, an overlap existed in the results of CII for the buccally and palatally positioned impacted canines (Tables 3 and 4). However, in the coronal and middle zones, a significant difference existed in the results of CII for the palatally and buccally positioned impacted canines. This difference within these ranges enables accurate localization of the impacted canines based on CII. In other words, in the middle and coronal zones, the impacted canine is buccally positioned if the CII is between 0.78-1.1 and palatally positioned if the CII is between 1.15-1.75.

Table 3- The mean, standard deviation and range of changes in CII for the buccally positioned impacted teeth

Vertical Orientation

N

Range

Mean

Standard deviation

Apical

2

0.91-1.48

1.18

0.17

Middle

2

1-1.1

1.03

0.03

Coronal

7

0.78-1.02

0.93

0.07

Middle+ coronal

9

0.78-1.1

0.94

0.07

Table 4- The mean, standard deviation and range of changes in CII for the palatally positioned impacted teeth

Vertical Orientation

N

Range

Mean

Standard deviation

Apical

1

1.15-1.3

1.26

0.05

Middle

13

1.15-1.75

1.28

0.12

Coronal

3

1.15-1.32

1.22

0.06

Middle+ coronal

16

1.15-1.75

1.26

0.12

The results of t-test yielded a P value of 0.001 for the middle and coronal zones; however, the P value for the apical zone was 0.151.

The values for CCI are shown in Tables 5 and 6. As seen, the CCI varied from 0.87 to 1.07 for the buccally positioned impacted teeth in the middle and coronal zones. This range was 1.09-1.44 for the palatally positioned impacted canines.

Table 5- The mean, standard deviation and range of changes of CCI in buccally positioned impacted canines

Vertical Orientation

N

Range

Mean

Standard deviation

Apical

2

1.13-1.38

1.28

0.13

Middle

2

0.94-1

0.94

0.04

Coronal

7

0.87-1

0.97

0.05

Middle+ coronal

9


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Nikneshan S, Hosseinzadeh M, Dehghanpour barooj M, Kheirkhahi M. Localization of Impacted Maxillary Canine Teeth: A Comparison between Panoramic and Buccal Object Rule in Intraoral Radiography. J Dent Sch. 2017; 35 (1) :31-40
URL: http://jds.sbmu.ac.ir/article-1-1574-fa.html
Localization of Impacted Maxillary Canine Teeth: A Comparison between Panoramic and Buccal Object Rule in Intraoral Radiography. مجله دانشکده دندانپزشکی دانشگاه علوم پزشکی شهید بهشتی. 1396; 35 (1) :31-40

URL: http://jds.sbmu.ac.ir/article-1-1574-fa.html

دوره 35، شماره 1 - ( 1-1396 ) برگشت به فهرست نسخه ها
مجله دانشکده دندانپزشکی دانشگاه علوم پزشکی شهید بهشتی Shahid Beheshti University Dental Journal
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