Knowledge and Awareness Regarding Partial Edentulism Among House Maids

Keywords

Inferior Alveolar Nerve(IAN); Impacted Third Molars(ITM); Inferior Mandibular Third Molar (IMTM); Mental Foramen (MF); Mandibular Canal (MC); Panoramic Tomography (PTG); Cone Beamed Computed Tomography (CBCT).

Introduction

Mandibular canals (MC) are anatomical structures that extend bilaterally from the Mandibular foramen to the Mental Foramen (MF) carrying the inferior alveolar nerves,arteries, and veins [1].

Interestingly, the most commonly affected nerve is the mandibular nerve (ie, reports indicate up to 64.4% of complications are related to thisnerve), followed by the lingual nerve [2]. Encroachment into this vital structure is amost unpleasant experience for both the patient and the dentist [3]. Complications, such as changes in sensation, numbness, pain, and excessive bleeding, can affect the patient’s overall quality of life. The iatrogenic nature of this condition significantly increases the psychological effects related to this damage [4, 5].

The assessment of the location of the mandibular canal, its course, as well as the relation of the third mandibular molar to the Inferior alveolar nerve is often a prerequisite for an appropriate planning. Hence, the radiographic examination has to, in some patients, include cross-sectional tomography [6]. Several studies report the frequency of postoperative IAN injury ranges from 0.4% to 8%, with less than 1% reporting permanent numbness. However, the probability of injury could be more than 10% in higher-risk individuals. Clinical studies have investigated the risk factors related to IAN injury, suchas age, sex, the depth of impaction, and angulation. It has also been reported that the proximityof the LM3 to the inferior alveolar canal (IAC), the relative position between the IAC and the roots of the LM3, and the shape of the IAC in the panoramic tomography (2d) and sagittal (3d) view of cone beam computed tomography (CBCT) are important factors to avoid IAN injury [7].

Material and Methods

This retrospective study was conducted at Department of Oral & Maxillofacial surgery, Thai Moogambigai Dental College and Hospital, Dr. M.G.R Educational and Research Institute (Deemed to be University), Chennai – 600037. Modern Lab &X-rays, East Moggapair, Chennai. The study protocol was approved by the Institutional Ethical Committee.A total of 120 cases Mandibular CBCT were obtained and assessed in this study. All were in the age group of 16 to 46 years (meanage=31years) of either gender.

Inclusion Criteria

1. Patients having age group ranging from 16 years to 46 years (meanage=31years) of either gender.

2. Presence of one or both impacted mandibular third molar. 3. Good quality images with respect to geometric accuracy and contrast of the image.

4. No deep caries, large restorations, root canal treatment in the lower teeth.

5. No super numerary tooth.

6. Devoid of positioning errors.

7. Images free from the presence of implants orany artifacts.

Exclusive Criteria

1. Presence of artifacts

2. Presence of maxillo facial trauma

3. Presence of pathological lesion in the mandible

4. Completely edentulous mandible

Radiation exposure includes Single CBCT scan–36.9 to 50.3µSv. The radiographic exposure for patients was well below the maximum permissible dose of 2.4mSvas per the NCRP guidelines [8]. In panoramic tomography (2d) images, the inferior alveolar nerve courseis marked from the point it starts from the mandibular foramen till the exit of the nerve through mental foramen. In Sagittal Sections of CBCT, the distance from the inferior alveolar nerve to the third mandibular molaris measured. The CBCT images of our study are presented in the following pictures.

Statistical Analysis

The collected data were analyzed using Statistical package for social sciences (SPSS) version 24.0, IBM Corporation. The categorical data were analyzed using chi square statistical test for testing the association be-tween the categorical variables. And the continuous data were analyzed using Non parametric Kruskal-wallis test for significance testing as the data were non- normally distributed which is checked by Shapiro-wilkis testing.

Results

Out of 120 cases, we found most frequently occurring type of impactionis Mesio angular (66%) type of impaction followed by Vertical (14%), Horizontal (11%) and Distoangular (9%) [Figure 1]. Most common type of course of inferior alveolar nerve is found to be Progressive Descent (56%), Caternary (30%), Linear (14%) [Figure 2]. There exists no significant association between the type of impaction with the course of alveolar nerve [Table 1]. The course of alveolar nerve was statistically equally distributed with all types of impaction in our study subjects. The Mean distance of the mandibular canal to the root apices of the mandibular third molar is found to be 0.8mm [Table 2].

Normality testing with Shapiro wilkis test reveals that as there exist a significance value of less than 0.05, it means that the continuous measurements data were not normally distributed [Table 3]. CBCT images showed that the Inferior alveolar nerve descends downwards from the mandibular foramen and the course of the inferior alveolar nerve progress more lingually near the third molar region, and near the second molar region more centrally and near the first molar region thenerve courses towards the buccal bone and while reaching the premolar region the nerve further progress more buccally and exits out through the mental foramen in buccal bone.

×

Figure 1:

Close

Figure 1. Distribution of type of impaction among study population.

×

Figure 2:

Close

Figure 2. Distribution of type of course of alveolar nerve among study population.

×

Table 1:

Close

Table 1. Association between the types of impaction with the course of alveolar nerve.

×

Table 2:

Close

Table 2. Descriptive characteristics of the continuous variable.

×

Table 3:

Close

Table 3. Normality testing of the continuous variable.

Discussion

In CBCT reconstructed 3D images, the morphology of alveolar ridge and the height of alveolar bone can be accurately displayed [9, 10], showing buccol ingual thickness, mesiodistal width, clear local bone structures and their anatomical relationship with surrounding anatomical structures, especially inferior alveolar nerve tube and the maxillary sinus. These images can assist to determine the volume of the bone, and the position, direction and volume of the implants, which are of great value for pre implanting planning [11, 12].

Three-dimensional views acquired by cone beam computed tomography (CBCT) have been introduced because of the improbability and limitations of 2-dimensional plain radiography. Also, the prognosis of the impaction can be accurately assessed when the exact position of an impacted tooth and its relationship with the surrounding anatomical structures is well known [13]. The present study was done to evaluate the intimate relationship between mandibular canal and impacted mandibular third molar such as distance from the third molarroot apex to the mandibularcanal, course of mandibular canal and type of impaction.

In our study, 216 Impacted mandibular third molars were assessed according to angulation (Winter‘s classification) into four groups namely mesioangular, distoangular, vertical, and horizontal depending upon the longaxis of third molar inrelation to the longaxis of second molar [14] in CBCT images and it was found that most common was Mesioangular type (66.3%), followedbyVertical (13.8%),Horizontal (10.6%), and Distoangular (9.3%) (Figure 1). Our results co-relates with Gulicher et al [15] (Mesioangular - 46.48%, Vertical - 33.2%, Distoangular - 15%, Horizontal - 5%), T. Hasegawaetal [16] Mesioangular-40.6%,Vertical-28.1%, Hoizontal- 28.1%, Distoangular-3.12%), Tachinamietal [17] (Mesioangular- 52.4%, Horizontal-28.2%, Vertical-19.35%), S.L.Queketal [18] (Mesioangular-62.7%,Horizontal-18.5%,Distoangular-10.36%, Vertical-10%), Musthafa et al [19] (Mesioangular - 56%, Vertical - 18.6%, Horizontal -16.6%, Distal -8.6% ), Venta et al [20]( Mesioangular - 64.2%, Vertical -21%, Distoangular - 7.1%, Horizontal - 7.1%) .

The study of Peterson etal (1993) [21] concluded that the most common mandibular third molarimpaction is mesioangular type (43%), then vertical (38%), distoangular (6%), and horizontal (3%). Sedaghatfar et al (2005) [22] in their study found maximum number of mandibular third molars to be mesioangular. Hazza’a et al (2006) [23] found highest number of vertically placed mandibular third molars followed by mesioangular, distoangular, and horizontal third molars. Chu et al(2003) [24] found that maximum number of third molars (80% of 3178 mandibular third molars) was horizontal or mesioangular. These variations in angular position of mandibular third molarsmay be because of the fact that the studied population in each study was quite different from each other.

Ozturk et al [25] confined classifiedthe canal’s course in the mandibular body as three types: 1)straight projection (12.2%), 2)catenary-like con-figuration (51.1%), and 3) progressively descending from posterior to anterior (36.7%). This study classified the course of the mandibular canal into linear, spoon-shaped, elliptic, and turning curve types, as in the study conducted by Liu et al [26]. A linear curve (22.9%) in our study was very similar to the straight projection (12.2%) observed by Ozturk et al, and the other curves were not similar to their findings.

Yun-Hoa Jung et al [27] in their study the distribution of course of nerve canal was Linear - 22.9%, Elliptical - 64.6%, Spoon - 6.8%, Turning -5.5%. Elliptical curves were most frequently observed along the course of the mandibular canal. The percentage of clearly visible mandibular canals was the highest among the spoon-shaped curves and the lowest among the linear curves. Sanam Mirbeigi et al [28] in his study on 156 patients–found 33.3% canals was straight type, 33.3% had Catenary type and 33.3% of them were presented with Progressive descending type. There was not statistically significant difference between two genders (P=0.092).

Ayla Ozturk et al [25] classified course of mandibular canal into 3 types:straight projection(12.2%), catenary-like configuration (51.1%), and progressive descent from posterior to anterior (36.7%). In our study, we found Progressive descent as most frequently occurring pattern -56.48%, followed by Caternary pattern - 29.6%, Linear pattern -13.8%. Trustiya et al [29]in their study found the average distance from the IMTM to the superior border of the IAC (LT-SC) was 1.76 ±0.96 mm in women and1.69 ±1.05 mminmen. The previous study of Mominetal [30] found the mean distance from apex of IMTM roots to canal to be 1.99 mm. The study of Liu et al [26] found that the distance from distal root of the IMTM to the superior border ofthe IAC was 1.27±1.66 mm. From the previous studies, it can be concluded that the average distance from tooth to canal is approximately 1-2 mm, and this value can be used for evaluation and prediction before surgical removal of the IMTM.

Prasanna srinivas Deshpande et al [31] stated that the overall mean distance from the impacted mandibular third molar stoinferior alveolar canal was-0.50 mm. Most of the samples (61.8 %) extended beyond the superior border of the inferior alveolar canal with a mean distance of -1.40 mm. Mesioangular impactions were found to be in the close proximity (-1.14mm) to inferior alveolar canal than any other type.

Michael Miloroetal [32] stated that the mean distance from erupted mandibular third molar teeth to the inferior alveolar canal is 0.88 mm. This distance was significantly different from unerupted teeth (P = .002). The mean values for un erupted teeth indicated that the most inferior portion of all teeth measured was below the superior border of the canal (negativevalues) as follows: mesioangular (20.97mm), vertical (20.61mm), distoangular (20.31 mm), and horizontal (20.24 mm). The position of mesioangular impactions were significantly different than all other impactiongroups (P = .0125. In our study the mean distance from the tooth apices of third molar to the mandibular canal was 0.8mm which corelates with Trustiya et al, Momin et al, Liu et al, Micheal Miloro et al and other previous studies.

Summary and Conclusion

The present study was aimed to assess the course of mandibular nerve from its entry to exit from mental canal and to evaluate the relation and distance of the inferior alveolar nerve canal to 3rd molar, and type of impaction. In this study, frequency of mesio angular impaction is 66.3%,Verticalis13.8%, Horizontalis 10.6% and Distoangularis 9.3%. The sagittal sections of CBCT showed alveolar nerve course with Progressive descent type- 122 (56.45%), Caternary type-64(29.6%), Linear type-30(13.8 %). In our study it is known that there exists no significant associationbetween the type of impaction with the course of alveolar nerve.The course of the alveolar nerve were statistically equally distributed with all types of impaction in our study subjects (Pvalue<0.05).

In this study, the mean distance from the root apices of third molar to the mandibular canal is 0.8mm. which states that the mandibular canal passes more lingually in the third molar region. There is no significant difference inthe distance of inferior alveolar nerve with the impacted tooth among typeof impaction and also there is no significant difference in distance between mandibular canal to buccal and lingual bone with the impacted tooth among different type of impaction.

CBCT images showed that the inferior alveolar nerve descends downwards from the mandibular for amen and the course of the inferior alveolar nerve progress more lingually near the third molar region, and near thesecond molar region more centrally and near the first molar region the nerve courses towardsthe buccalbone and while reaching the premolar region the nerve further progress more buccally and exits out through the mental foramenin buccal bone.

In conclusion, our study can guide oral surgeons and can be applied toevaluate and predict the relationship between the IMTM and the IAC before surgeries such as Extraction of third molar, Placement of intra osseous implants, Placement of screws, Bilateral sagittal split osteotomy, Inferior Alveolar Nerve lateralization, Genioplasty in orthognathic surgery, Body osteotomy, Distraction Osteogenesis, and Massetrichypertrophy.